Mania that develops in depressed patients who are undergoing ECT is relatively uncommon and may occur more frequently in bipolar patients. The authors' review of three cases illustrates the importance of the clinician distinguishing mania from organic euphoric states that can also develop during ECT. Severity of cognitive impairment and the presence of silly or inappropriate laughter are useful in making this distinction. Capacity to clinically evaluate the persistence of depressive symptoms should determine whether ECT can continue when an organic euphoric state develops.