The authors report on 62 inpatients over age 60 who met DSM-III-R criteria for bipolar disorder, divided into early- and late-onset groups by their median age at lifetime onset, 49 years, in order to examine differences in demographic and clinical characteristics, treatment parameters, and outcome in the two groups during a short-term hospitalization. The late-onset group was more likely to have psychotic features and to demonstrate cerebrovascular risk/burden. However, both groups had similar and highly significant improvements in the Brief Psychiatric Rating Scale, Global Assessment Scale, and the Mini-Mental State Exam, and 87% were able to be discharged to settings no more restrictive than those at admission.