Objective: To assess the efficacy of electroconvulsive therapy (ECT) in DSM-5 obsessive-compulsive-related disorders (OCRDs) and conditions subsumed under an "extended" OCD spectrum, including tic disorders and self-injurious behaviors. Data Sources: A systematic search of the MEDLINE, Web of Science, Scopus, and LILACS databases and other sources was performed between June 6 and July 2, 2017. Search terms included (Autis*) AND (ECT OR electroconvulsive), (Self-injur*) AND (ECT OR electroconvulsive), (Tic* OR Tourette) AND (ECT OR electroconvulsive), (Body Dysmorphic Disorder OR Dysmorphophobi*) AND (ECT OR electroconvulsive), (Hoard*) AND (ECT OR electroconvulsive), (Trichotillomani*) AND (ECT OR electroconvulsive), (Skin Picking OR Excoriation) AND (ECT OR electroconvulsive), (Grooming) AND (ECT OR electroconvulsive), (Kleptomani*) AND (ECT OR electroconvulsive), and (Pyromani*) AND (ECT OR electroconvulsive). No search restrictions (ie, date, language, or document type) were used. Study Selection: Fifty-two records that described the individual responses of OCRDs to ECT (involving 69 patients) were selected. Data Extraction: Clinical data and responses of individual cases were recorded. Data from responders were compared to nonresponders. Results: All records were case reports or case series; there were no randomized controlled trials. Of the 69 OCRD participants who had undergone ECT, a positive response was reported in 73.4% of the cases (including 44.0% of the BDD, 74.1% of the tic disorder, and 85.7% of the self-injurious behavior patients). At follow-up, the majority of responders who had abstained from further ECT had experienced relapse. However, a positive response was obtained in all participants who received a new course of ECT. Patients who responded positively to ECT were likely to report previous unsuccessful treatment with antipsychotics (P < .001) and antidepressants (P = .007). Conclusions: The finding that more than 70% of the reviewed cases showed some response to ECT should not be considered unequivocal evidence of its efficacy in OCRDs. The available evidence suggests that a randomized controlled trial of ECT in OCRDs may be warranted, particularly in severe tic disorders and self-injurious behaviors.