OBJECTIVE: Maintenance electroconvulsive therapy (maintenance ECT) has emerged as an alternative treatment for patients who relapse repeatedly or cannot tolerate psychotropic medications. The pattern of maintenance ECT use in two university-affiliated hospitals was surveyed to evaluate its effectiveness in treating several disorders, establish treatment guidelines, and identify adverse side effects. METHODS: Records of 161 patients who received ECT from 1976 through 1988 were reviewed retrospectively. Nine patients who received maintenance ECT-- prophylactic ECT treatments administered for longer than six months-- were identified. The presence of target symptoms and behaviors in the periods before and after administration of maintenance ECT was compared. RESULTS: All nine patients experienced a complete or a significant partial remission of target symptoms. Six of the nine patients were ready for transfer to less restrictive settings. Given the small number of patients, treatment guidelines could not be established; however, patients with mood disorder required less frequent treatments than patients with thought disorder. Adverse effects were documented for two of the nine patients, but they were not severe enough to discontinue treatment. CONCLUSIONS: For this sample, maintenance ECT was a safe, efficacious, and well-tolerated treatment with minimal side effects. Further, controlled studies are warranted.