Oscar-winner Robin Williams has entered himself into rehab for alcohol abuse, according to "Entertainment Tonight."

"After 20 years of sobriety, Robin Williams found himself drinking again and has decided to take proactive measures to deal with this for his own well-being and the well-being of his family," a Williams rep tells "ET." "He asks that you respect his and his family's privacy during this time. He looks forward to returning to work this fall to support his upcoming film releases."

Williams has always discussed his battles with drug and alcohol addiction frequently in his comedy routines.

The "Good Will Hunting" co-star had a minor hit earlier this summer with the family comedy "RV" and can currently be seen on the big screen in "The Night Listener."

Additional information will almost certainly appear on tonight's "Entertainment Tonight," and check out Zap2it for any updates.