Background: Prospective data on chemotherapy for elderly patients with metastatic breast cancer (MBC) remain scarce. We compared the efficacy and safety of first-line chemotherapy with pegylated liposomal doxorubicin (PLD) versus capecitabine in MBC patients aged ≥65 years in a multicentre, phase III trial. Patients and methods: Patients were randomized to six cycles of PLD (45 mg/m2 every 4 weeks) or eight cycles of capecitabine (1000 mg/m2 twice daily, day 1-14 every 3 weeks). Results: The study enrolled 78 of the planned 154 patients and was closed prematurely due to slow accrual and supply problems of PLD. Many included patients were aged ≥75 years (54%) and vulnerable (≥1 geriatric condition: 71%). The median dose intensity was 85% for PLD and 84% for capecitabine, respectively. In both arms, the majority of patients completed at least 12 weeks of treatment (PLD 73%; capecitabine 74%). After a median follow-up of 39 months, 77 patients had progressed and 62 patients had died of MBC. Median progression-free survival was 5.6 versus 7.7 months (P = 0.11) for PLD and capecitabine, respectively. Median overall survival was 13.8 months for PLD and 16.8 months for capecitabine (P = 0.59). Both treatments were feasible, grade 3 toxicities consisting of fatigue (both arms: 13%), hand-foot syndrome (PLD: 10%; capecitabine: 16%), stomatitis (PLD: 10%; capecitabine: 3%), exanthema (PLD: 5%) and diarrhoea (PLD: 3%; capecitabine: 5%). Only 1 of 10 patients aged ≥80 years completed chemotherapy, while 3 and 6 patients discontinued treatment due to toxicity or progressive disease, respectively. Conclusion: Both PLD and capecitabine demonstrated comparable efficacy and acceptable tolerance as first-line single-agent chemotherapy in elderly patients with MBC, even in vulnerable patients or patients aged ≥75 years. However, patients aged ≥80 years were unlikely to complete chemotherapy successfully.