OBJECTIVE: To compare adjunctive long-acting injectable risperidone plus treatment as usual (RLAI+TAU) versus TAU alone for relapse, rehospitalization, and urgent care events in patients with bipolar disorder in routine care settings. METHODS: This was a 12-month randomized open comparison of RLAI+TAU (n = 20) and TAU alone (n = 25) in adults with rapid cycling, Mini International Neuropsychiatric Interview-confirmed bipolar I/II disorder and 4 or more illness relapses in the preceding 12 months. Clinical outcome was assessed every 2 weeks using the Longitudinal Interval Follow-up Evaluation instrument. Psychopathology and quality of life were assessed monthly using the Young Mania Rating Scale, Montgomery-Asberg Depression Rating Scale, Quick Inventory of Depressive Symptoms-Self Report 16 and Quality of Life, Enjoyment, and Satisfaction Questionnaire. Relapse was defined using symptom severity, necessary clinical adjustment of medications, and urgent care referrals. Relapse rates and duration were calculated per person per year of follow-up. All treatments were provided by community-based clinicians. RESULTS: There were no significant between-groups differences in the total number or duration of relapse events (any cause) or in the number of manic or depressive relapses. Thirteen of 14 urgent care events (hospitalization, emergency department visit, intensive outpatient, or respite care referral) occurred with TAU alone (92.3%). Urgent care referral (P < 0.04) and necessary medication change rates (P = 0.01) were significantly lower in the RLAI+TAU group. There were no significant between-groups differences in the duration of follow-up, hospitalization rates, or psychopathology over time. CONCLUSIONS: Rates of any-cause relapse may not differ significantly between RLAI+TAU and TAU alone; however, RLAI may reduce the need for urgent care referrals or the frequency of medication adjustments to prevent relapse in community-treated patients with rapid cycling bipolar disorder. Additional investigation is warranted. Copyright © 2011 by Lippincott Williams &Wilkins.