In an interview with BBC Radio 2 in Britain, Perry admitted that he has no recollection of three years' worth of the show -- from Seasons 3 through 6 -- because he was under the influence of alcohol and drugs most of the time.
"I don't remember three years of it," Perry, 46, responded, when asked to name his least favorite episode of the show. "So none of those. ... I was a little out of it."
The Odd Couple star, who entered rehab during Season 7 of Friends, has been candid about his struggles with addiction to Vicodin and alcohol. The rest of his Friends co-stars reunited on Sunday to film a segment for NBC's Must See TV: A Tribute to James Burrows, which will air on Feb. 21. Perry, who is currently in rehearsals in London for his upcoming play The End of Longing, will appear on the special to introduce the rest of the cast.