To say that the fact-based comedy-drama "Patch Adams" wouldn't work without Robin Williams might be the understatement of the year.

In fact, this predictable, heavy-handed comedy-drama is lucky it works at all, given that it comes from the "Ace Ventura" and "The Nutty Professor" filmmaking team (director Tom Shadyac and screenwriter Steve Oedekerk).

But it does have Williams, who finally unleashes his formidable comedic talents after some relatively restrained roles lately (especially the ironically titled "What Dreams May Come").

In fact, the idea behind this fact-based film (inspired by physician Hunter "Patch" Adams' tongue-in-cheek biography, "Gesundheit: Good Health is a Laughing Matter") recalls "Good Morning, Vietnam," which set Williams in the middle of a dramatic battlefield, where he knocked down his opponents with humor.

And though both Williams and the film stray into some questionable areas of humor, he succeeds quite nicely at pulling it off.

Adams is played as a brilliant but troubled young man who finds his true calling by accident. Institutionalized for depression, he discovers he has a talent for healing (by practicing reverse psychology on some of his fellow patients), and he gains his nickname, "Patch."

Upon his release from the institution (he simply decides to leave), Patch enrolls in the Medical College of Virginia, where he excels academically and begins to practice an unorthodox form of healing — laughter. He provokes the patients to laugh at his antics and they start forgetting about their pain.

While his fellow students — including his cohort Truman (Daniel London) and the beautiful but dedicated Carin (Monica Potter) — are won over by compassion, he butts heads with the school's by-the-book instructor, Dean Walcott (Bob Gunton).

In fact, he finds himself in danger of being expelled unless he can prove to his instructors that he belongs there.

Admittedly, Williams is much too old to be playing this role (Adams wasn't really much older than his fellow students). And Oedekerk's script is filled with far too many "noble" speeches and drippy sentiment.

However, it's a joy to see Williams finally go wild again, and there's no denying that many of the outrageous jokes are a scream (including one tasteless but funny sight gag that has to be seen to be believed).

The rest of the cast is also quite good — except for Gunton, whose stuffed-shirt character becomes a bit unrealistic.

"Patch Adams" is rated PG-13 for vulgar sexual humor, sexual references and other crass gags, profanity and some male nudity.