Among 97 chronic marijuana users, 9 per cent were found to have had multiple life problems as a consequence of their marijuana use when evaluated during a 5-year follow-up study. Operationally defined criteria for marijuana abuse are presented which are analogous to criteria commonly used in diagnosing alcoholism. These criteria identified marijuana abusers who manifested many problems from marijuana use, including fighting, panic attacks, and traffic tickets. This was in contrast to the majority of the chronic users who did not have multiple complications from tneir marijuana use. The marijuana abusers had used marijuana more frequently, had used greater amounts of marijuana, and had begun using it at an earlier age than nonabusers. A high rate of alcoholism was found in the abusers but was not statistically greater than in nonabusers. The objective criteria presented here offer a method for simple, prompt evaluation of potential problems from marijuana use.