This randomized multicenter phase III trial evaluated the role of maintenance therapy with pegylated liposomal doxorubicin (PLD) after induction chemotherapy in patients with metastatic breast cancer (MBC). Patients without disease progression following first-line induction chemotherapy consisting of three cycles of doxorubicin (75 mg/m(2)) followed by three cycles of docetaxel (100 mg/m(2)) both every 21 days, were randomized to PLD (40 mg/m(2)) every 28 days for six cycles or to observation. Time to progression (TTP) was the primary endpoint. 288 patients were enrolled and received induction first-line chemotherapy. One hundred and fifty-five achieved response or stable disease and were randomized to maintenance PLD (n = 78) or observation (n = 77). With a median follow-up of 20 months from randomization (range 1-56), disease progression occurred in 94% of patients. PLD significantly improved TTP by 3.3 months (8.4 vs. 5.1 months; hazard ratio [HR] = 0.54, 95% CI: 0.39 to 0.76, P = 0.0002) compared with observation. Overall survival was not significantly prolonged with PLD (24.8 vs. 22.0 months, respectively; HR = 0.86, 95% CI: 0.58-1.27, P = 0.44). PLD-induced toxicity was mild and manageable with up to 5% of patients experiencing grade 3/4 non-hematologic events (fatigue, mucositis, palmar-plantar erythrodysesthesia). Grade 3/4 neutropenia occurred in 12% of patients; two patients developed febrile neutropenia. This phase III trial demonstrated that maintenance chemotherapy with PLD is well tolerated and offers improved TTP in patients with MBC following first-line chemotherapy.