The DSM-III criteria for post-traumatic stress disorder (PTSD) were derived clinically and have been substantiated in the literature only by self-report data while evaluation of these same criteria with more objective measures has been overlooked. This study provided a laboratory-based evaluation of the DSM-III criterion symptoms of PTSD with six symptoms of the disorder which were operationalized as cognitive, behavioral and psychophysiological measures. The responses of 16 Vietnam combat veterans who met the criteria for a PTSD diagnosis were compared to those of 16 well-adjusted combat veterans without PTSD. Dependent measures were obtained twice, following exposure to first control and then combat auditory stimuli. Results showed that five of the six measures were effective in differentiating the two combat veteran groups. These findings provided experimental support and construct validity for five DSM-III criteria of PTSD. The implications of these findings for the DSM-III-R PTSD diagnostic criteria are discussed.