Ziprasidone has modest QTc-prolonging effects, but it is not known whether this translates into an increased risk of cardiovascular events. To address this issue, a large, international, open-label, randomized, post-marketing study, the Ziprasidone Observational Study of Cardiac Outcomes (ZODIAC), has been conducted to compare the cardiovascular safety of ziprasidone and olanzapine. Between February 2002 and February 2006, over 18,000 patients with schizophrenia from 18 countries were enrolled from a variety of psychiatry practice settings. A physician-administered questionnaire collected baseline information on demographics, medical and psychiatric history, and concomitant medication use. Data were self-reported by patients or reported by enrolling physicians. Descriptive baseline data on 18,094 patients with schizophrenia are presented here. Patients (mean age, 41.6 years; 55.1% male; 60.0% white) came primarily from the United States or Brazil (73.0%). Approximately 18% of patients had hypertension, 14.8% had hyperlipidemia, 46.5% currently smoked, 28.9% had a body mass index of ≥30 kg/m2, and 7.7% had diabetes at baseline; all of these characteristics are major cardiovascular risk factors. Mean time since schizophrenia diagnosis was 10.4 years, and average Clinical Impression Score was 5.2 (range, 1-8). At baseline, 71% of patients were using antipsychotic drugs. Although almost 80% of patients were using concomitant medications, less than 3% were using antihypertensive drugs or statins. In conclusion, the ZODIAC baseline data suggest that this study population has a substantial prevalence of cardiovascular risk factors and that hyperlipidemia and hypertension may be undertreated.