Two pivotal, phase III, randomised, placebo-controlled, registration trials (MM-009 and MM-010) showed that lenalidomide plus dexamethasone was more effective than placebo plus dexamethasone in the treatment of patients with relapsed or refractory multiple myeloma. This pooled, retrospective subanalysis of MM-009 and MM-010 analysed outcomes according to patient age. A total of 704 patients (390 aged <65 years, 232 aged 65–74 years, and 82 aged ≥75 years) received lenalidomide or placebo, both in combination with dexamethasone. The overall response rate (ORR) was significantly higher in patients treated with lenalidomide plus dexamethasone versus placebo plus dexamethasone in all age groups (P < 0.0001 for all). Median progression-free survival (PFS) and median time-to-progression (TTP) were similar, and both were significantly longer with lenalidomide plus dexamethasone in all age groups (P < 0.001 for all). Median overall survival (OS) favoured lenalidomide plus dexamethasone in all age groups, although the difference was not statistically significant. Adverse events of anaemia, febrile neutropenia, deep-vein thrombosis, neuropathy, and gastrointestinal disorders increased with age. Lenalidomide combined with dexamethasone improved the ORR and prolonged PFS, TTP, and OS compared with placebo plus dexamethasone, irrespective of age. This finding was consistent with the overall MM-009 and MM-010 populations.