Adult respiratory distress syndrome (ARDS) from overdose of tricyclic antidepressants (TCA) has been reported but is not well known. During a 1-year period, 81 patients with serious overdose from tranquilizers and other psychotropic drugs were examined. TCA alone induced overdose in 30 patients or were combined with other drugs in 26 patients. Twenty-five (31%) patients had overdose from drugs other than TCA. Chest radiography revealed that 30 (54%) patients with TCA overdose and six (24%) patients with non-TCA overdose had abnormalities. Clinical and radiographic findings consistent with ARDS were noted in five (9%) patients with TCA overdose and none of the patients with non-TCA overdose. Five patients with TCA overdose and one (4%) patient with non-TCA overdose had interstitial edema that never progressed to ARDS. TCA should be added to the list of drugs associated with the development of ARDS.