This study compared the risks of cardiovascular morbidity and mortality in people with schizophrenia who use antipsychotic medications to risks in individuals without schizophrenia in a large managed care organization. A sample of 1920 schizophrenia patients was matched by age, sex, date, and health plan to 9600 persons randomly selected from the health plan general membership. Death, myocardial infarction, arrhythmia, and new-onset diabetes were identified using a National Death Index search and medical claims records. The adjusted all-cause mortality rate in the group of treated schizophrenics was four times higher than in the control group regardless of whether patients were given a typical or an atypical antipsychotic medication. Users of typical antipsychotics had a fivefold higher risk of myocardial infarction than the control subjects. Among patients with schizophrenia, cardiovascular risk was inversely associated with intensity of use of antipsychotic drugs, suggesting that the observed risks may not be due to a simple or direct effect of drugs. Patients treated for schizophrenia had higher rates of new-onset diabetes than did the general population controls. This risk was most pronounced in persons with more intense exposure to drugs and appeared to be indistinguishable in users of typical antipsychotics, of atypical products, or of both.