Symptoms, functioning, and mental health service use were compared in older outpatients with bipolar disorder and unipolar depression. Bipolar outpatients (n = 37, mean age = 69.7) had higher total symptom severity and positive symptom scores, more impaired community-living skills, and earlier age at onset of illness than patients with unipolar depression (n = 85, mean age = 70.9). Bipolar elderly patients used almost four times the total amount of mental health services and were four times more likely to have had a psychiatric hospitalization over the previous 6 months. These findings underscore the need for effective services for elderly patients with bipolar disorder, who account for a minority of patients with affective disorders, but use a disproportionate amount of costly services.