The purpose of the present study was to describe the oral health status and treatment requirements and to study the association between dental caries and mental illness in a group of hospitalized psychiatric patients.A total of 326 psychiatric patients were examined and compared with 156 normal persons of comparable age and sex. 75.5% of the psychiatric patients exhibited caries experience with significantly higher DMFT and DMFS compared to the 66% in controls. Stepwise regression analysis demonstrated that DMFT was related to age, type of the ward and duration of mental illness. Periodontal diseases were significantly higher among psychiatric patients than controls. Higher proportion of psychiatric patients were suffering from TMJ disorders. Further, extensive dental treatment requirements were observed among these patients.