Google says it is "appalled" that its new Photos app mistakenly labelled a black couple as being "gorillas".
Its product automatically tags uploaded pictures using its own artificial intelligence software.
The error was brought to its attention by a New York-based software developer who was one of the people pictured in the photos involved.
Google was later criticised on social media because of the label's racist connotations.
"This is 100% not OK," acknowledged Google executive Yonatan Zunger after being contacted by Jacky Alcine via Twitter.
"[It was] high on my list of bugs you 'never' want to see happen."
Mr Zunger said Google had already taken steps to avoid others experiencing a similar mistake.