"After recent events, Chris was forced to take a clear look at a problem he has been trying to deal with himself for years," his rep tells Us. "He understands now that he can not beat this disease alone. He thanks everyone for their support as he takes all the necessary steps to deal with his addiction and asks for privacy while doing so."
On Friday, a source tells Us the American Pie actor, 31, checked into a 30-day alcohol addiction program at the Cirque Lodge in Utah, where actresses Eva Mendes and Mary Kate Olsen have been treated.
He may stay longer than a month if need be.
Last Wednesday, Klein was arrested on suspicion of drunk driving in L.A. His blood alcohol level was three times the legal limit of .08.
He was also arrested on drunk-driving charges in 2005.
Klein split with actress Ginnifer Goodwin in 2008. Before that, he was engaged to Katie Holmes.