Dysfunctional thought patterns are presumed to underlie cognitive biases in mood disorder patients. However, few studies have compared dysfunctional thought patterns in bipolar manic and unipolar depressed patients. Cognitive schemas and dysfunctional attitudes were evaluated using the cognitive checklist for mania and Dysfunctional Attitudes Scale (DAS) in 34 bipolar manic, 35 unipolar depressed, and 29 nonpsychiatric control subjects. Unipolar depressed subjects had significantly higher total DAS scores and subfactor scores as compared with nonpsychiatric controls, whereas bipolar patients had intermediate scores between both groups. Significant correlations emerged between cognitive checklist for mania total and subcomponent scores and the DAS (total, performance subfactor, and approval subfactor scales) for the bipolar, but not the unipolar or nonpsychiatric control groups. Core beliefs among bipolar patients appear negativistic during manic phases, potentially reflecting an overcompensation for depression. The findings support clinical approaches targeting depressive cognitions regardless of the presence of manic symptoms.