Aggressive, escape and point-maintained operant responding of male marijuana smokers were measured during six 25-min sessions conducted over an 8-h experimental day. Aggressive responding ostensibly subtracted points exchangeable for money from another subject. Escape responding protected the subject's counter from point subtractions initiated by the other subject for some period of time. Aggressive and escape responding were engendered by subtracting points from the subjects and maintained by initiation of intervals free of point subtractions. Point subtractions presented to the subjects were attributed to other persons. Subjects earned points exchangeable for money on a third response option. Subjects participated in one session prior to smoking and five sessions after smoking. Subjects smoked placebo or three different potencies of active marijuana cigarettes. Marijuana smoking effects on escape responding were not significant and depended upon the frequency of provocation. Point-maintained responding was decreased after marijuana smoking. Aggressive responding was increased for the first hour after smoking and returned to placebo levels later in the day. These effects of marijuana smoking on aggressive responding are discussed in terms of subject characteristics, particularly drug use history.