Abstract: Mixed manic/depressive episodes in patients with bipolar disorder are underdiagnosed because of restrictive diagnostic criteria. Using the broader definition of a mixed episode represented by the Cincinnati criteria, we reevaluated the medical records of patients with bipolar disorder hospitalized for a manic episode. We also examined the predictive power of previously unrecognized depressive symptoms. Of 520 inpatients with mania, we retrospectively diagnosed 59 (11.3%) as having a probable mixed episode. Compared with the patients with pure mania, the patients with mixed episodes were more likely to have a family history of psychiatric illness, comorbid personality disorder, and a history of suicide attempts. Binary logistic regression revealed that loss of interest, loss of energy, feelings of worthlessness, and feelings of helplessness had good positive predictive value (>0.7) for mixed episodes. Accurate diagnosis of mixed episodes may require a broadening of diagnostic criteria and emphasis on symptoms such as loss of interest, loss of energy, and feelings of worthlessness and helplessness.