This study examines the Standardized Mortality Ratio (SMR) by age, sex and cause of death among psychiatric inpatients in Singapore. Mortality in mentally ill inpatients was found to be 2.79 times that of the general population. The SMR decreased with age and the SMR for those 70 years and above was lower than that reported in the literature. The mortality ratio was most accentuated in the younger patients, especially in the female. Excess mortality was observed in both the natural as well as the unnatural causes of death. Among the natural causes of death, infection and pneumonia showed high excess in mortality. In the unnatural causes of death, suicide was predominant.