BACKGROUND Few studies have investigated the association of psychiatric morbidity with acute hospitalization risk in elderly people. METHODS We examined this association using population-based data for 1092 older adults aged > or =60 years in Singapore, including subjects who reported at least one acute hospitalization from any medical condition(s) in the 12 months prior to interview (N = 136). Psychiatric morbid/comorbid disorders were diagnosed using the Geriatric Mental State examination. RESULTS In a multivariate analysis, comorbid psychiatric disorders were independently associated with hospitalization [adjusted odds ratio 2.76, 95% confidence interval 1.20-6.33], after controlling for age, ethnicity, employment status, number of medical comorbidities, number of activities of daily living limitations, hearing and visual impairment, SF-12 Physical and Mental Component Summary scores, social, productive, fitness and health activities, and regular visits to health-care providers. Neither dementia diagnosis nor cognitive impairment measured by the Mini-mental State Examination was associated with increased hospitalization risk. CONCLUSIONS Psychiatric morbidity in old age was significantly associated with increased hospitalization risk. This finding underlines the importance of treating psychiatric illness to reduce the risk of acute hospitalization in elderly patients.