Alan Alda played Dr. Gabe Lawrence (season 6). He previously played the famous role of Dr. Benjamin Franklin "Hawkeye" Pierce on the famous TV drama "M*A*S*H".

Sally Field played Abby's mother, Maggie Wyczenski (season 7). She has played many roles, including the ex-wife of Robin William's character in Mrs. Doubtfire, and the role of Forest Gump's mother. (Yes, the one who says, "Life is like a box of choclates. You never know what your gonna get.")

John Cullum played Mark's father, David Greene (season 6).Has previously been on "Northern Exposure" and "All my Children.

James Belushi guest starred in the episode "Piece of Mind" (season 7). He is known for a variety of film roles.

James Cromwell played Bishop Stewart(season 7). He has previously been in Babe, Deep Impact, and The Green Mile. gonna get.")

Rosemary Clooney played Madame X, aka Mary Cavanaugh in the episodes "The Gift" and "Going Home" (season 1). She was a famous actress of the 50's in such films as White Christmas andDeep in My Heart. She is also George Clooney's aunt.

Red Buttons played Jules Rubadoux, the husband of an elderly woman Carter is treating(season 2). He had his own show in the 50's, "The Red Buttons Show."

Sanford Meisner guest starred in the episode "Sleepless in Chicago" (season 1). He was regarded by many as one of the three greatest acting teachers ever.

Swoosie Kurtz played Tina Marie Chambliss in "Suffer the Little Children" (season 4). She has been in such movies as Dangerous Liasons and Liar, Liar.

Don Cheadle played med student Paul Nathan (season 9). He has been in such movies as The Family Man, Traffic and Ocean's Eleven.

Tom Everett Scott played Eric Wyzenski (season 9). He has been in That Thing You Do, Boiler Room, and Dead Man on Campus.

Hallee Hirsh played Rachel Greene (Seasons 8-9). She had previously played Tom Hanks' aunt in You've Got Mail.

David Schwimmer of Friends fame had an uncredited cameo as Dr. Karubian in the episode "Dr. Carter, I Presume" (Season 3).

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Mackenzie Phillips played Leslie Miller in "Damage is Done" (Season 8). She played Carol in both American Graffiti
and More American Graffiti.

Patrick Fugit played a young man with testicular cancer (Season 9). He starred in the film Almost Famous.

Michael Ironside played Doctor 'Wild Willy' Swift in several episodes in Season 1. He had previously played 'Jester' in Top Gun, alongside Anthony Edwards.