SCHEDULE 13G

Amendment No. 
Lam Research Corporation
common stock
Cusip # 512807108
Filing Fee: Yes


Cusip # 512807108
Item 1:	Reporting Person - FMR Corp. - (Tax ID:  04-2507163)
Item 4:	Commonwealth of Massachusetts
Item 5:	116,800
Item 6:	None
Item 7:	2,895,250
Item 8:	None
Item 9:	2,895,250
Item 11:	12.29%
Item 12:	HC 




Cusip # 512807108
Item 1:	Reporting Person - Edward C. Johnson 3d - (Tax ID:  029-24-9996)
Item 4:	United States of America
Item 5:	None
Item 6:	None
Item 7:	2,895,250
Item 8:	None
Item 9:	2,895,250
Item 11:	12.29%
Item 12:	IN 




SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)


Item 1(a).	Name of Issuer:

		Lam Research Corporation

Item 1(b).	Name of Issuer's Principal Executive Offices:

		4650 Cushing Parkway, 
		Fremont, CA  94538

Item 2(a).	Name of Person Filing: 

		FMR Corp.

Item 2(b).	Address or Principal Business Office or, if None, Residence:

		82 Devonshire Street, Boston, Massachusetts  02109

Item 2(c).	Citizenship:

		Not applicable

Item 2(d).	Title of Class of Securities:

		Common Stock

Item 2(e).	CUSIP Number:  

		512807108

Item 3.	This statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) and the 
person filing, FMR Corp., is a parent holding company in accordance 
with Section 240.13d-1(b)(ii)(G).  (Note:  See Item 7).

Item 4.	Ownership

	(a)	Amount Beneficially Owned:
	2,895,250

	(b)	Percent of Class:
	12.29%

	(c)	Number of shares as to which such person has:  

	(i)	sole power to vote or to direct the vote:
	116,800

	(ii)	shared power to vote or to direct the vote:
	None

	(iii)	sole power to dispose or to direct the disposition of:
	2,895,250

	(iv)	shared power to dispose or to direct the disposition 
of:	None




Item 5.	Ownership of Five Percent or Less of a Class.

	Not applicable.

Item 6.	Ownership of More than Five Percent on Behalf of Another Person.

	Various persons have the right to receive or the power to 
direct the receipt of dividends from, or the proceeds from the 
sale of, the common stock of Lam Research Corporation.  The 
interest of one person, Fidelity Magellan Fund, an investment 
company registered under the Investment Company Act of 1940, in 
the common stock of Lam Research Corporation, amounted to 
1,851,700 shares or 7.86% of the total outstanding common stock 
at April 30, 1994.  

Item 7.	Identification and Classification of the Subsidiary Which Acquired 
the Security Being Reported on By the Parent Holding Company.

	See attached Exhibit(s) A, B, and C.

Item 8.	Identification and Classification of Members of the Group.

	Not applicable, see attached Exhibit A. 

Item 9.	Notice of Dissolution of Group.

	Not applicable.


Item 10.	Certification.

	By signing below I certify that, to the best of my knowledge 
and belief, the securities referred to above were acquired in 
the ordinary course of business and were not acquired for the 
purpose of and do not have the effect of changing or 
influencing the control of the issuer of such securities and 
were not acquired in connection with or as a participant in any 
transaction having such purpose or effect.


Signature

	After reasonable inquiry and to the best of my knowledge and 
belief, I certify that the information set forth in this 
statement is true, complete and correct. 



	May 5, 1994	
Date



	/s/Arthur S. Loring
Signature



	Arthur S. Loring, Vice 
President	
Name/Title




SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)

	Pursuant to the instructions in Item 7 of Schedule 13G, Fidelity 
Management & Research Company ("Fidelity"), 82 Devonshire Street, Boston, 
Massachusetts 02109, a wholly-owned subsidiary of FMR Corp. and an investment 
adviser registered under Section 203 of the Investment Advisers Act of 1940, 
is the beneficial owner of 2,772,450 shares or 11.77% of the common stock 
outstanding of Lam Research Corporation ("the Company") as a result of acting 
as investment adviser to several investment companies registered under Section 
8 of the Investment Company Act of 1940.  The number of shares of common stock 
of Lam Research Corporation owned by the investment companies at April 30, 
1994 included 180,800 shares of common stock resulting from the assumed 
conversion of $4,520,000 principal amount of 6% Convertible Subordinated 
Debentures (40 shares of common stock for each $1,000 principal amount of 
debenture).

	The ownership of one investment company, Fidelity Magellan Fund, amounted 
to 1,851,700 shares or 7.86% of the common stock outstanding.  Fidelity 
Magellan Fund has its principal business office at 82 Devonshire Street, 
Boston, Massachusetts 02109.  

	Edward C. Johnson 3d, FMR Corp., through its control of Fidelity, and the 
Funds each has sole power to dispose of the 2,772,450 shares owned by the 
Funds.

	Neither FMR Corp. nor Edward C. Johnson 3d, Chairman of FMR Corp., has 
the sole power to vote or direct the voting of the shares owned directly by 
the Fidelity Funds, which power resides with the Funds' Boards of Trustees.  
Fidelity carries out the voting of the shares under written guidelines 
established by the Funds' Boards of Trustees.

	Fidelity Management Trust Company, 82 Devonshire Street, Boston, 
Massachusetts 02109, a wholly-owned subsidiary of FMR Corp. and a bank as 
defined in Section 3(a)(6) of the Securities Exchange Act of 1934, is the 
beneficial owner of 6,700 shares or 0.03% of the common stock outstanding of 
the company as a result of its serving as investment manager of the 
institutional account(s).  

	FMR Corp., through its control of Fidelity Management Trust Company, has 
sole dispositive power over 6,700 shares and sole power to vote or to direct 
the voting of 700 shares, and no power to vote or to direct the voting of 
6,000 Shares of common stock owned by the institutional account(s) as reported 
above.

	Edward C. Johnson 3d owns 34.0% of the outstanding voting common stock of 
FMR Corp.  Mr. Johnson 3d is Chairman of FMR Corp.  Various Johnson family 
members and trusts for the benefit of Johnson family members own FMR Corp. 
voting common stock.  These Johnson family members, through their ownership of 
voting common stock, form a controlling group with respect to FMR Corp.

	Fidelity International Limited, Pembroke Hall, 42 Crowlane, Hamilton, 
Bermuda, and various foreign-based subsidiaries provide investment advisory 
and management services to a number of non-U.S. investment companies (the 
"International Funds") and certain institutional investors.  Fidelity 
International Limited is the beneficial owner of 116,100 shares or 0.49% of 
the common stock outstanding of the company.  Additional information with 
respect to the beneficial ownership of Fidelity International Limited is shown 
on Exhibit B, page 9.


SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)


	Pursuant to instructions in Item 7 of Schedule 13G, this Exhibit has been 
prepared  to identify Fidelity International Limited, Pembroke Hall, 42 Crow 
Lane, Hamilton, Bermuda, a Bermudian joint stock company incorporated for an 
unlimited duration by private act of the Bermuda Legislature (FIL) and an 
investment adviser to various investment companies (the "International Funds") 
and certain institutional investors, as a beneficial owner of the 116,100 
shares or 0.49% of the common stock outstanding of Lam Research Corporation.

	Prior to June 30, 1980, FIL was a majority-owned subsidiary of Fidelity 
Management & Research Company (Fidelity), a wholly-owned subsidiary of FMR 
Corp.  On that date, the shares of FIL held by Fidelity were distributed, as a 
dividend,  to the shareholders of FMR Corp.  FIL currently operates as an 
entity independent of FMR Corp. and Fidelity.  The International Funds and 
FIL's other clients, with the exception of Fidelity and an affiliated company 
of Fidelity, are non-U.S. entities.

	A partnership controlled by Edward C. Johnson 3d and members of his 
family owns shares of FIL voting stock with the right to cast approximately 
47.22% of the total votes which may be cast by all holders of FIL voting 
stock.  Mr. Johnson 3d is Chairman of FMR Corp. and FIL.  FMR Corp. and FIL 
are separate and independent corporate entities.  FMR Corp. and FIL are 
managed independently and their Boards of Directors are generally composed of 
different individuals.  Their investment decisions are made independently, and 
their clients are different organizations.

	FMR Corp. and FIL are of the view that they are not acting as a "group" 
for purposes of Section 13(d) under the Securities Exchange Act of 1934 (the 
"1934" Act) and that they are not otherwise required to attribute to each 
other the "beneficial ownership" of securities "beneficially owned" by the 
other corporation within the meaning of Rule 13d-3 promulgated under the 1934 
Act.  Therefore, they are of the view that the shares held by the other 
corporation need not be aggregated for purposes of Section 13(d). However, FMR 
Corp. is making this filing on a voluntary basis as if all of the shares are 
beneficially owned by FMR Corp. and FIL on a joint basis.

	FIL may continue to have the International Funds or other accounts 
purchase shares subject to a number of factors, including, among others, the 
availability of shares for sale at what FIL considers to be reasonable prices 
and other investment opportunities that may be available to the International 
Funds.

	FIL intends to review continuously the equity position of the 
International Funds and other accounts in the Company.  Depending upon its 
future evaluations of the business and prospects of the Company and upon other 
developments, including, but not limited to, general economic and business 
conditions and money market and stock market conditions, FIL may determine to 
cease making additional purchases of shares or to increase or decrease the 
equity interest in the Company by acquiring additional shares, or by disposing 
of all or a portion of the shares.

	FIL does not have a present plan or proposal which relates to or would 
result in (i) an extraordinary corporate transaction, such as a merger, 
reorganization, liquidation, or sale or transfer of a material amount of 
assets involving the Company or any of its subsidiaries, (ii) any change in 
the Company's present Board of Directors or management, (iii) any material 
changes in the Company's present capitalization or dividend policy or any 
other material change in the Company's business or corporate structure, (iv) 
any change in the Company's charter or by-laws, or (v) the Company's common 
stock becoming eligible for termination of its registration pursuant to 
Section 12(g)(4) of the 1934 Act.

	FIL has the sole power to vote and the sole power to dispose of 116,100 
shares.  


SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)

RULE 13d-1(e)  AGREEMENT

	The undersigned persons, on May 5, 1994, agree and consent to the joint 
filing on their behalf of this Schedule 13G in connection with their 
beneficial ownership of the common stock of Lam Research Corporation at April 
30, 1994.

	FMR Corp.
	By	/s/Arthur S. Loring
Arthur S. Loring
Vice President - Legal
		Edward C. Johnson 3d
	By	/s/Arthur S. Loring
Arthur S. Loring
Under Power of Attorney dated 
5/17/89
On File with Schedule 13G for
Airborne Freight Corp. 9/10/91
	Fidelity Management & Research Company
	By	/s/Arthur S. Loring
Arthur S. Loring
Sr. V.P. and General Counsel
	Fidelity Magellan Fund
	By	/s/Arthur S. Loring
Arthur S. Loring
Secretary