One hundred regular marihuana users and 50 nonuser friends were interviewed by a psychiatrist. A high lifetime incidence of psychopathology was found in both groups. Half of each group fulfilled criteria for some psychiatric diagnosis. One third received a diagnosis of primary affective disorder. Among users, 12% received a diagnosis of sociopathy compared to none of the controls. Almost every diagnosed psychiatric illness among the users began before first marihuana use. Alcohol, tobacco, sexual experience, "acting out" behavior in limit-testing areas usually antedated marihuana experience. It is concluded that at least some regular marihuana users come from a population at high risk for psychiatric problems, and that these difficulties almost always preceed use of marihuana.