To test the efficacy and safety of corticotropin-based immunotherapies in pediatric opsoclonus-myoclonus syndrome, 74 children received corticotropin alone or with intravenous immunoglobulin (groups 1 and 2, active controls); or both with rituximab (group 3) or cyclophosphamide (group 4); or with rituximab plus chemotherapy (group 5) or steroid sparers (group 6). There was 65% improvement in motor severity score across groups (P < .0001), but treatment combinations were more effective than corticotropin alone (P = .0009). Groups 3, 4, and 5 responded better than group 1; groups 3 and 5 responded better than group 2. The response frequency to corticotropin was higher than to prior corticosteroids (P < .0001). Fifty-five percent had adverse events (corticosteroid excess), more so with multiagents (P = .03); and 10% had serious adverse events. This study demonstrates greater efficacy of corticotropin-based multimodal therapy compared with conventional therapy, greater response to corticotropin than corticosteroid-based therapy, and overall tolerability.