Between 1972 and 1974, the outcomes of army enlisted men who had served in Vietnam during 1970–71 were evaluated and compared with that of a matched group. This paper reports the major findings of that study with respect to frequency of narcotic addiction in and after Vietnam, and the major risk factors for Vietnam addiction and later relapse. Extraordinary access to records facilitated drawing the sample, locating it, and verifying interview responses. The surprisingly low levels of readdiction and the rarity of addiction to narcotics alone as compared with poly-substance dependence are findings still not entirely incorporated into public and scientific views of heroin addiction. Some defenses against that incorporation are examined.