A case-control study was conducted in men who were of draftable age during the Vietnam conflict to examine the association of soft tissue sarcomas (STSs) with military service in Vietnam as well as other host and environmental risk factors. A total of 217 STS cases selected from the Armed Forces Institute of Pathology were compared to 599 controls for Vietnam service, occupational and nonoccupational exposure to various chemicals, occupational history, medical history, and life-style (smoking, alcohol, coffee, etc.). Military service information was verified by a review of the patient's military personnel records. Other information was ascertained from a telephone interview with either subjects or their next of kin. Cases and controls were stratified on the basis of the hospital type (civilian, Veterans Administration, and military); the Mantel-Haenszel estimate of the odds ratio (OR), adjusted for the effects of the stratification variable, was calculated. Vietnam veterans in general did not have an increased risk of STS when compared to those men who had never been in Vietnam (OR, 0.85; 95% confidence interval, 0.54-1.36). Subgroups of Vietnam veterans who had higher estimated opportunities for Agent Orange exposure seemed to be at greater risk of STSs when their counterparts in Vietnam were taken as a reference group. However, this risk was not statistically significant.