Background: Bipolar disorder is a chronic illness with a 2-year recurrence rate of approximately 50% among individuals receiving treatment in the community. The aim of this 18-month, open-label, continuation study was to evaluate the long-term safety and effectiveness of lurasidone in patients who initially presented with a major depressive episode associated with bipolar disorder, and who had completed at least 6 months of initial treatment with lurasidone. Methods: Patients with bipolar I depression were enrolled in one of three 6-week, double-blind, placebo-controlled trials (monotherapy with lurasidone, 1 study; adjunctive therapy with lurasidone; and lithium or valproate, 2 studies). Study completers were eligible for a 6-month, open-label extension study of lurasidone utilizing flexible daily doses of 20-120 mg; extension completers were then eligible for an additional 18 months of continuation treatment with flexible, once-daily doses of lurasidone in the range of 20-80 mg. Concomitant therapy with mood stabilizers was permitted throughout the open-label extension and continuation studies. Results: A total of 1199 patients entered, and 941 (78.5%) completed initial, double-blind, acute treatment, of whom 817/941 (86.8%)entered, and 559 (68.4%) completed the 6-month extension study; 122/559 patients (21.8%) entered the 18-month continuation study, of whom 19.7% of discontinued, including 6.6% due to adverse events and 1.6% due to insufficient efficacy. The mean dose of lurasidone during the 18-month continuation study was 61.8 mg/day, and the modal dose was 60 mg/day. Mean change in weight, from acute baseline to 18-month continuation endpoint was +0.8 kg (completers, n = 55); median changes in cholesterol and triglycerides were -3.0 mg/dL and +26.0 mg/dL, respectively. Based on a Kaplan-Meier analysis, the probability of relapse during 18 months of continuation treatment with lurasidone was estimated to be 18.3% in the monotherapy group and 29.1% in the adjunctive therapy group. Improvement in global illness severity was also maintained during 18 months of continuation therapy (CGI-S at continuation baseline, 2.1; 18-month completers, 1.7; LOCF-endpoint, 1.9). Conclusions: Up to 2 years of treatment with lurasidone was safe and well tolerated in this bipolar disorder population presenting with an index episode of depression. Improvement in depressive symptoms was maintained in the majority of patients treated with lurasidone, with relatively low rates of relapse, and with minimal effects on weight and metabolic parameters.