The interim Liberal leader talked about his drug use after giving a speech to his caucus on Wednesday.
Asked if he ever smoked pot, Rae replied "of course I did."
"I don't think anybody of my generation could be regarded as an abstainer but have I done it in recent memory? The answer would be no," Rae told 680News.
Rae's comments came as the Liberal Party prepares for its biennial convention in Ottawa this weekend. The Young Liberals have put forward a resolution to legalize and regulate marijuana, which will be debated during the meeting.
As of Thursday afternoon, the resolution had the fourth largest number of votes on the party's website, behind resolutions for democratic renewal, preferential balloting and clean energy development, but ahead of electoral reform and a host of other issues.
Despite his past drug use, Rae has said he will not support the resolution.
Rae's student days also made headlines for an entirely different reason Thursday. Declassified documents, obtained by The Canadian Press, revealed the RCMP spied on Rae when he was a member of the student council at the University of Toronto during the late 1960s.
"The notion that any of this posed a kind of a threat to the established order certainly would have come as news to all of us," he said in an interview.
The debate on the Liberal resolution to legalize pot will take place on the heels of a heavily-publicized study suggesting marijuana doesn't damage the lungs in the same way tobacco does. Researchers found that smoking a joint once a week doesn't harm the lungs.
That should be good news for supporters of the Young Liberals' resolution, but even if it passes at the convention it will almost certainly have no effect on policy.
The Conservative government strengthened drug penalties as part of its omnibus crime bill. The legislation could result in jail time for growing as few as six plants.
A recent Justice Department study found new mandatory minimum provisions in the crime bill could result in a spike in the number of people sent to jail for marijuana-related offences.
Rae expressed his fears of just that outcome on Wednesday. "(The legislation) is unworkable and frankly a waste of time with the part that deals with the drug issue. I don't think it's effective and I don't think it's going to work and I think it's going to end up jamming up our courts and jamming up our jails."