The comedian, who has been candid about his battle with alcohol and substance abuse in the past, has checked into a treatment facility to "focus on his commitment" to overcome his addictions.
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Robin Williams has checked into rehab to 'focus on his continued commitment' to sobriety
"After working back-to-back projects, Robin is simply taking the opportunity to fine-tune and focus on his continued commitment, of which he remains extremely proud," his rep said.
"This was totally planned and scheduled," a source told E! News. "He's been working for about 18 months straight. He had some time off so us using it to do a check-in."
Robin, 62, sought treatment for alcohol addiction in 2006; he also battled substance abuse as he rose to fame as a comedian in the Seventies, but managed to kick his habit when his first wife became pregnant with their eldest son Zachary in 1982.
"Cocaine for me was a place to hide," he told People in 1988. "Most people get hyper on coke. It slowed me down."
Robin Williams, pictured with his wife Susan, has been candid about his struggle with addiction
Last September, Robin spoke to Parade about falling off the wagon after 20 years of sobriety while filming The Big White in 2005.
"One day I walked into a store and saw a little bottle of Jack Daniels. And then that voice - I call it the 'lower power' – goes, 'Hey. Just a taste. Just one'," the actor said. "I drank it and there was that brief moment of, 'Oh, I'm ok!' But it escalated so quickly.
"Within a week I was buying so many bottles I sounded like a wind chime walking down the road. I knew it was really bad one Thanksgiving when I was so drunk they had to take me upstairs."
At the insistence of his family, Robin went off to rehab. "It was not an intervention so much as a ultimatum," he admitted. "Everyone kind of said, 'You've got to do this'. And I went, 'Yeah, you're right.'"