Document and Entity Information	Total
Prospectus:
Document Type	497
Document Period End Date	Sep. 30, 2022
Entity Registrant Name	HARRIS ASSOCIATES INVESTMENT TRUST
Entity Central Index Key	0000872323
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Oct. 01, 2022
Document Effective Date	Oct. 01, 2022
Prospectus Date	Jan. 28, 2022
Oakmark Fund \| Investor Class
Prospectus:
Trading Symbol	OAKMX
Oakmark Fund \| Advisor Class
Prospectus:
Trading Symbol	OAYMX
Oakmark Fund \| Institutional Class
Prospectus:
Trading Symbol	OANMX
Oakmark Fund \| R6 Class
Prospectus:
Trading Symbol	OAZMX
Oakmark Select Fund \| Investor Class
Prospectus:
Trading Symbol	OAKLX
Oakmark Select Fund \| Advisor Class
Prospectus:
Trading Symbol	OAYLX
Oakmark Select Fund \| Institutional Class
Prospectus:
Trading Symbol	OANLX
Oakmark Select Fund \| R6 Class
Prospectus:
Trading Symbol	OAZLX
Oakmark Global Fund \| Investor Class
Prospectus:
Trading Symbol	OAKGX
Oakmark Global Fund \| Advisor Class
Prospectus:
Trading Symbol	OAYGX
Oakmark Global Fund \| Institutional Class
Prospectus:
Trading Symbol	OANGX
Oakmark Global Fund \| R6 Class
Prospectus:
Trading Symbol	OAZGX
Oakmark Global Select Fund \| Investor Class
Prospectus:
Trading Symbol	OAKWX
Oakmark Global Select Fund \| Advisor Class
Prospectus:
Trading Symbol	OAYWX
Oakmark Global Select Fund \| Institutional Class
Prospectus:
Trading Symbol	OANWX
Oakmark Global Select Fund \| R6 Class
Prospectus:
Trading Symbol	OAZWX
Oakmark International Fund \| Investor Class
Prospectus:
Trading Symbol	OAKIX
Oakmark International Fund \| Institutional Class
Prospectus:
Trading Symbol	OANIX
Oakmark International Fund \| Advisor Class
Prospectus:
Trading Symbol	OAYIX
Oakmark International Fund \| R6 Class
Prospectus:
Trading Symbol	OAZIX
Oakmark International Small Cap Fund \| Investor Class
Prospectus:
Trading Symbol	OAKEX
Oakmark International Small Cap Fund \| Advisor Class
Prospectus:
Trading Symbol	OAYEX
Oakmark International Small Cap Fund \| Institutional Class
Prospectus:
Trading Symbol	OANEX
Oakmark International Small Cap Fund \| R6 Class
Prospectus:
Trading Symbol	OAZEX
Oakmark Equity and Income Fund \| Investor Class
Prospectus:
Trading Symbol	OAKBX
Oakmark Equity and Income Fund \| Advisor Class
Prospectus:
Trading Symbol	OAYBX
Oakmark Equity and Income Fund \| Institutional Class
Prospectus:
Trading Symbol	OANBX
Oakmark Equity and Income Fund \| R6 Class
Prospectus:
Trading Symbol	OAZBX

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