Previous studies attempting to support unipolar mania as an entity distinct from bipolar disorder, have produced conflicting results. The present study reports on a chart review of 247 patients admitted to the University of Iowa with a history of at least one manic episode; 87 of these had apparently never experienced a depression. A subgroup of 92 patients, who met DSM III diagnostic criteria and had a history of at least two episodes of affective disorder, were also examined. There were few clinically meaningful differences between patients with unipolar mania and bipolar disorder on demographic, symptomatic, or familial variables. An earlier report that unipolar manics were more likely to be male and have a family history of unipolar depression was not confirmed. Unipolar mania is not supported as a separate entity from bipolar disorder.