Cigarette smoking and other forms of drug abuse are more prevalent among schizophrenics than the general population. Despite the clinical importance of this problem, there has been relatively little experimental study of schizophrenic drug use. We examined under controlled laboratory conditions the effects of response requirement and the availability of an alternative (monetary) reinforcer on cigarette smoking by schizophrenics. Subjects were six heavy smokers with diagnoses of schizophrenia or schizoaffective disorder. Before each session, subjects provided carbon monoxide samples indicating recent smoking abstinence. During 3-h sessions, subjects obtained opportunities to smoke (2 puffs/opportunity) under a fixed ratio (FR) schedule of reinforcement, which varied across sessions from FR50 to FR6400. In half of the sessions, subjects also were able to earn a small amount of money ($0.25/ratio completed) under an FR400 schedule. Increasing the response requirement for smoking decreased smoking and increased smoking-maintained responding. The availability of the monetary reinforcer decreased smoking and smoking-maintained responding by approximately half. These results are consistent with those seen previously in community volunteers without major mental illness studied under the same experimental conditions, suggesting that smoking by these two populations is controlled, at least in part, by a common set of determinants.