We reviewed the pre-Vietnam contents of the service medical and personnel records of 250 Vietnam combat veterans, in an attempt to identify factors predisposing to the development of posttraumatic stress disorder (PTSD). PTSD and non-PTSD veterans did not differ significantly on self-reported medical history items, sick call visits, or military efficiency and conduct ratings. There were trends for PTSD veterans to have lower arithmetic aptitude, more self-reported school difficulties, and (paradoxically) lower pulse rate at military induction.