A retrospective study was conducted of 14 affectively ill patients who were treated with long-term unilateral maintenance electroconvulsive therapy (MECT). The patients had received an inpatient course of ECT before being referred for MECT. The average age was 57 ± 16 years (range 30–91). The average interval between inpatient ECT was 2.4 ± 0.9 days, in contrast to the interval between MECT, which was 12.1 ± 11.3 days. The average time to start MECT after inpatient ECT was 16.2 ± 16.2 days. The average duration of MECT was 81 ± 104 days (maximum 571). Patients' affective symptoms continued to improve during the course of MECT based on Carroll Depression Ratings. Adjustment of the electrical dose and caffeine augmentation were used to keep the seizure durations >30 s by electroencephalograph (EEG) monitoring. Over time, most treatments were administered using the maximal charge provided by the Mecta SR-1. Despite considerable time intervals between MECT treatments, seizure durations did not increase. Additionally, high stimulus charge and frequently administered caffeine were used to maintain seizure length. The apparent anticonvulsant effect of ECT was not lost over the time span of MECT. This has clinical implications if the anticonvulsant effects of ECT contribute to determining the clinical response.