Background: While electroconvulsive therapy (ECT) has been used for many years, there is insufficient research regarding the indications for continuation/maintenance (C/M)-ECT, its safety and efficacy, and the characteristics of patients with schizophrenia or schizoaffective disorder who receive multiple ECT sessions. The aims of this study were to characterize a series of patients who received 30 ECT sessions or more, to describe treatment regimens in actual practice, and to examine the results of C/M-ECT in terms of safety and efficacy, especially the effect on aggression and functioning. Methods: We performed a retrospective chart review of 20 consecutive patients (mean age 64.6 years) with schizophrenia (n=16) or schizoaffective disorder (n=4) who received at least 30 ECT sessions at our ECT unit, and also interviewed the treating physician and filled out the Clinical Global Impression-Severity, Global Assessment of Functioning, and the Staff Observation Aggression Scale-Revised. Results: Patients received a mean of 91.3 ECT sessions at a mean interval of 2.6 weeks. All had been hospitalized for most or all of the previous 3 years. There were no major adverse effects, and cognitive side effects were relatively minimal (cognitive deficit present for several hours after treatment). We found that ECT significantly reduced scores on the Staff Observation Aggression Scale-Revised subscales for verbal aggression and self-harm, and improved Global Assessment of Functioning scores. There were reductions in total aggression scores, subscale scores for harm to objects and to others, and Clinical Global Impression-Severity scores, these were not statistically significant. Conclusion: C/M-ECT is safe and effective for chronically hospitalized patients. It improves general functioning and reduces verbal aggression and self-harm. More research using other aggression tools is needed to determine its effects and to reproduce our findings in prospective and controlled studies [ABSTRACT FROM AUTHOR]