Daniel Radcliffe, Rupert Grint and Emma Watson, who play young wizards Harry Potter, Ron Weasley and Hermione Granger, say they have experimented just like all other teenagers.
Emma, 17, said: "You are careful not to do it in the public eye. You have your first cigarette or first glass of alcohol in a safe environment with your close friends - or you could be foolish and choose to do it in a London nightclub."
18-year-old Rupert added: "Because we are quite busy we do miss out, but we still have those kinds of experiences like getting drunk for the first time."
Despite enjoying going out, Daniel, 17, says he always puts his work first.
He revealed: "What I enjoy most is the acting and the work, but it doesn't stop us from having a party once in a while. Parties are fine and fun."