The authors evaluated the validities of the DSM-III elements defining posttraumatic stress disorder (PTSD) in alcoholic Vietnam veterans by studying the relationships of each to qualification for a PTSD diagnosis under DSM-III standards, the history of a major stressor (3 or more months of combat), and the presence/absence of enough other problems to meet the symptomatic DSM-III requirements for this diagnosis. Elements dealing with the reexperiencing of traumas, diminished pleasure, detachment from others, hyperalertness, sleep disturbance, guilt over behaviors required for survival, and avoidance of stimuli reminiscent of traumas showed substantial correlations with eligibility for a PTSD diagnosis. However, items dealing with emotional expressiveness, response to intimacy, survival guilt, impaired memory, and trouble concentrating either failed to correlate with qualification for a PTSD diagnosis or yielded marginal results. One ("lacking direction") of 10 additional symptoms sometimes termed as "post-Vietnam syndrome" behaviors correlated with eligibility for a PTSD diagnosis as well. The present results and those described in earlier studies suggest that several modifications in the DSM-III definition of PTSD are desirable.