Background: A substantial number of patients with late-life depression (LLD) that remitted after ECT experience relapse. Identifying risk factors for relapse may guide clinical management to devote attention to those at increased risk. Therefore the current study aims to evaluate which baseline clinical characteristics are related to relapse within six months after successful ECT in patients with severe LLD. Methods: 110 patients with LLD from the prospective naturalistic follow-up Mood Disorders in Elderly treated with Electro-Convulsive Therapy (MODECT) study were included. A total of 73 patients (66.4%) remitted after ECT, six patients had missing information on relapse, rendering to a total sample size of 67 patients. Relapse within six months after ECT was defined as a Montgomery Åsberg Depression Scale (MADRS)-score > 15, readmission or restart of ECT. Logistic regression analyses were conducted to examine the association between baseline clinical characteristics and relapse. Results: A total of 22 patients (32.8%) experienced a relapse. Patients with psychotic depression were less likely to relapse (odds ratio = 0.32, p =.047), corrected for prior admissions; 76.9% of patients with psychotic depression remained remitted. Limitations: Due to its naturalistic design, no firm conclusions can be drawn on the effect of post-ECT treatment. Conclusions: Patients with psychotic depression had a lower risk to experience relapse after successful ECT. This result strengthens the hypothesis that psychotic depression might be a specific depression subtype with a favorable ECT outcome up to six months after ECT.