Relationships between psychiatric morbidity and interpersonal conflict at work among 15,530 Finnish employees aged 24 to 64 years were studied in a prospective follow-up: 4 years for all psychiatric hospitalizations, 5 years for suicide, and 6 years for long-term medication due to chronic psychosis. The association between interpersonal conflict at work and physician-diagnosed psychiatric morbidity was significant (RR 2.18, 95% CI 1.34-3.54) when results were adjusted for general health status, social class, and mental instability/stress. Results remained significant in additional models adjusted for neuroticism, marital status, conflict with spouse, and high alcohol consumption. The results were similar for both sexes.