Players who were - or became - medical doctors

[Brownieand45sfan]

Bobby Brown, Yankees
http://en.wikipedia.org/wiki/Bobby_Brown_(baseball)
http://www.baseball-reference.com/b/brownbo03.shtml

John Falk "Bob" Poser, White Sox, Browns
U. Wis. Class of '33
(Of The Poser Clinic, Wisconsin's 2nd oldest clinic, founded in 1896 by Edward Poser, Dr. Poser's father).
http://www.baseball-reference.com/p/poserbo01.shtml

Doc Gessler, Superbas, Tigers, Cubs, Senators, etc.
http://www.baseball-reference.com/g/gessldo01.shtml

Others?
Here is the list of players nick-named "Doc":
http://www.baseball-reference.com/player_search.cgi?search=doc

[Zito75]

How about "Moonlight" Graham?

[Utter Chaos]

George "Doc" Medich once saved the life of a fan who had a heart attack before a game. Also, in 1999 he was found guilty in a court of law for writing false prescriptions in the name of patients so that he could illegally obtain painkillers for himself. He was sentenced to nine years probabtion.

[Williamsburg2599]

John Lee Richmond: Boston Red Caps, Worcester Ruby Legs, Providence Grays, Cincinnati Red Stockings.
Brown University class of 1880
Hurler of the First Perfect Game in Professional Baseball History.
http://www.galanissportsdata.com/person.asp?personID=725
http://www.baseball-reference.com/r/richmle01.shtml
http://en.wikipedia.org/wiki/John_Lee_Richmond

[Utter Chaos]

"Doc" Casey and Jim Lonborg became Dentists.

[Brownieand45sfan]

"Doc" Casey (snip)
Life imitating TV? :)

[Brownieand45sfan]

How about "Moonlight" Graham?

Add 'em:

"After playing in the minor leagues through the 1907 season, Graham completed his medical degree from the University of Maryland in 1908. He obtained his license the following year and began practicing medicine in Chisholm, Minnesota."

[geezer]

Did Tito Landrum became an orthopedic surgeon or something like that?

[Gee Walker]

Ron Taylor, relief ace for the Cardinals and Mets in the sixties, got his MD and later became an orthopedic surgeon.