A study was conducted to investigate smoking patterns in 445 Vietnam veterans with and without posttraumatic stress disorder (PTSD). Combat veterans with PTSD reported similar occurrence of smoking (53%) compared to combat veterans without PTSD (45%). For those who smoked, combat veterans with PTSD reported a significantly higher rate of heavy smoking (> or = 25 cigarettes daily): 28% of combat veterans without PTSD were heavy smokers and 48% of combat veterans with PTSD were heavy smokers. PTSD diagnosis and heavy smoking status were independently and differentially related to motives for smoking. In combat veterans with PTSD, heavy smoking status was positively related to total health complaints, lifetime health complaints, health complaints in the past year, negative health behaviors, total PTSD symptoms, DSM-IV C cluster (avoidance and numbing) and D cluster (hyperarousal) PTSD symptoms. Heavy smoking status was also associated with fewer positive health behaviors.