SCHEDULE 13G  
  
Amendment No. 4  
KLA Instruments Corporation  
Common Stock  
Cusip # 482480100  
Filing Fee: No  
 
 
Cusip # 482480100  
Item 1:	Reporting Person - FMR Corp. - (Tax ID:  04-2507163)  
Item 4:	Commonwealth of Massachusetts  
Item 5:	600  
Item 6:	None  
Item 7:	1,977,300  
Item 8:	None  
Item 9:	1,977,300  
Item 11:	3.30%  
Item 12:	HC   
  
  
 
 
Cusip # 482480100  
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:	1,977,300  
Item 8:	None  
Item 9:	1,977,300  
Item 11:	3.30%  
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:  
  
		KLA Instruments Corporation  
  
Item 1(b).	Name of Issuer's Principal Executive Offices:  
  
		160 Rio Robles   
		San Jose, CA  95134  
  
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:    
  
		482480100  
  
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: 
	1,977,300  
  
	(b)	Percent of Class: 
	3.30%  
  
	(c)	Number of shares as to which such person has:    
  
	(i)	sole power to vote or to direct the vote: 
	600  
  
	(ii)	shared power to vote or to direct the vote: 
	None  
  
	(iii)	sole power to dispose or to direct the disposition of: 
	1,977,300  
  
	(iv)	shared power to dispose or to direct the disposition of: 
	None  
  
  
 
 
Item 5.	Ownership of Five Percent or Less of a Class.  
  
	If this statement is being filed to report the fact that as of  
the date hereof, the reporting person has ceased to be the  
beneficial owner of more than five percent of the class of  
securities, check the following (X).  
  
Item 6.	Ownership of More than Five Percent on Behalf of Another Person.  
  
	Not applicable.  
  
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 and B.  
  
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.  
  
	Inasmuch as the reporting persons are no longer the beneficial  
owners of more than five percent of the number of shares  
outstanding, the reporting persons have no further reporting  
obligation under section 13(d) of the Securities and Exchange  
Commission thereunder, and the reporting persons have no  
obligation to amend this Statement if any material change  
occurs in the facts set forth herein.  
  
  
Signature  
  
	After reasonable inquiry and to the best of my knowledge and  
belief, I certify that the information set forth in this  
Schedule 13G in connection with FMR Corp's beneficial ownership  
of the common stock of KLA Instruments Corporation at November  
30, 1995 is true, complete and correct.   
  
  
  
	December 7, 1995	  
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 1,946,700 shares or 3.25% of the common stock  
outstanding of KLA Instruments 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.    
  
	Edward C. Johnson 3d, FMR Corp., through its control of Fidelity, and the  
Funds each has sole power to dispose of the 1,946,700 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 30,600 shares or 0.05% of the common stock outstanding of  
the Company as a result of its serving as investment manager of the  
institutional account(s).    
  
	Edward C. Johnson 3d and FMR Corp., through its control of Fidelity  
Management Trust Company, has sole dispositive power over 30,600 shares and  
sole power to vote or to direct the voting of 600 shares, and no power to vote  
or to direct the voting of 30,000 Shares of common stock owned by the  
institutional account(s) as reported above.  
  
	Members of the Edward C. Johnson 3d family are the predominant owners of  
Class B shares of common stock of FMR Corp. representing approximately 49% of  
the voting power of FMR Corp.  Mr. Johnson 3d owns 12.0% and Abigail Johnson  
owns 24.5% of the aggregate outstanding voting stock of FMR Corp., and Mr.  
Johnson 3d is Chairman of FMR Corp.  The Johnson family group and all other  
Class B shareholders have entered into a shareholders' voting agreement under  
which all Class B shares will be voted in accordance with the majority vote of  
Class B shares.  Accordingly, through their ownership of voting common stock  
and the execution of the shareholders' voting agreement, members of the  
Johnson family may be deemed, under the Investment Company Act of 1940, to  
form a controlling group with respect to FMR Corp.   
  
 
 
SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS  
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)  
  
RULE 13d-1(f)(1)  AGREEMENT  
  
	The undersigned persons, on December 7, 1995, 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 KLA Instruments Corporation at  
November 30, 1995.  
  
	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