The literature on bipolar disorder in older adults is very limited, in spite of the fact that the elderly are a growing population in the United States. This retrospective record review study evaluated clinical characteristics and hospital-based resource use patterns among 48 older adults with bipolar disorder, and compared groups with early-onset (EOS) versus late-onset (LOS) bipolar disorder. The mean age of the group was 67.3 years, with no difference in age between EOS and LOS categories. Late onset illness was identified in 29.2% of the group (N = 14). Compared with individuals with EOS, individuals with LOS were 2.8 times more likely to be female. Both groups had extensive medical comorbidity (mean of 3.7 comorbid medical conditions), substantial hospital usage (mean length of stay, 14.8 days) and polypharmacy usage. Bipolar disorder with onset after age 50 is not uncommon among older adults hospitalized on a geropsychiatric unit. Clinical characteristics may differ between individuals with early-onset and late-onset bipolar illness, and resource utilization may be extensive in both groups.