This report describes the sudden appearance of mixed mania in three children with delusional depression soon after the commencement of tricyclic antidepressant therapy. The observation is consistent with reports linking psychomotor abnormalities and psychosis in severely depressed juveniles to an increased propensity for manic switching, as well as adult studies that report a greater risk of antidepressant-induced cycling in bipolar compared with unipolar affective illness. The cases described suggest the need for caution when considering tricyclic pharmacotherapy in juveniles with severe depressive disease.