OBJECTIVE: To describe the suicide rates of psychiatric in-patients in the canton of Zurich for the period 1992-2004, and to determine putative risk factors. METHOD: The data were derived from the psychiatric case register of the canton Zurich. The analyses were based on person-years calculations and standardised mortality ratios. Additional information was assessed via case records. RESULTS: During the 13-year period the standardised mortality ratio was 48.9. The risk of suicide was particularly high in patients with personality and affective disorders. Most suicides occurred during regular leave periods, despite the fact that clinical assessment had indicated there was no suicide risk for the patient. CONCLUSION: The suicide risk of in-patients is distinctly higher than in the general population. A better assessment of suicide risk before regular leave periods could lead to a decrease of suicides in in-patient settings, as well as a more rigorous treatment of borderline cases, and of affective and psychotic symptoms.