In many veterans, the post-Vietnam era is that of "post-traumatic stress disorder" (P.T.S.D.), chronic or delayed, practically corresponding to the traumatic neurosis, dominated at all times by the intrusive-repetitive syndrome. This phenomenon is considered as concerning at least 800,000 persons. Acting out, in fact less common than it was feared, may be associated with it, as well as delinquency, likely more frequent than in the general population, alcoholism and substance abuse. Regarding the latter, the notion of a "legacy of Vietnam" is very questionable. Its decrease, which is sometimes spontaneous, puts the question of dependency, including opiates. The evidence of a possible P.T.S.D. behind these miscellaneous behavior disorders which evoke more an antisocial personality, is ticklish. With regard to epidemiology, the part of psychiatric sequels of Vietnam is so much the more difficult to appreciate as the affective and social support provided to these people at the time of their return "into the world" is often poor. A partial induction of such troubles, inspired with ideological or utilitarian purposes, is not excluded.