How many guests appeared on mash?

A great deal. Here's the list of notable guest stars:

Antony Alda- (Alan Alda's brother) ("Lend a Hand" 8.20)

Robert Alda- (Alan Alda's father) ("The Consultant" 3.17 and "Lend a Hand" 8.20)

Ned Beatty- ("Dear Peggy 4.10)

Ed Begley Jr.- ("Too Many Cooks" 8.01)

James Cromwell- ("Last Laugh" 6.03)

Laurence Fishburne- ("The Tooth Shall Set You Free" 10.14)

Ron Howard- ("Sometimes You Hear the Bullet" 1.17)

Harry Morgan- ("The General Flipped at Dawn")

Pat Morita- ("Deal Me Out" 2.13 and "The Chosen People" 2.19)

Leslie Nielsen- ("The Ringbanger" 1.16)

Patrick Swayze- ("Blood Brothers" 9.18)