Given that the efficacy/safety of thalidomide for relapsed or refractory multiple myeloma have not been well characterized in a randomized, controlled setting, an analysis of larger, single-agent trials was conducted. Nine trials met the following inclusion criteria: primary population of multiple myeloma; all patients relapsed or refractory; single-agent thalidomide; and sample size > or =50. At median doses of 200 - 800 mg per day, the pooled overall response rate (ORR) was 28.2% (95% CI: 22.6 - 33.7%), including a complete response (CR) rate of 1.6% (95% CI: 0.3 - 2.9%) and partial response rate of 26.0% (95% CI: 20.1 - 32.0%). Response was typically based on M-protein reduction alone. Peripheral neuropathy (PN) incidence varied from 12 - 44%, possibly impacted by the short median follow-up (9 - 29 months). Pooled venous thromboembolism (VTE) incidence was 2.7% (95% CI: 1.1 - 4.3%) and discontinuation due to intolerance (DDI) rate was 14.9% (95% CI: 12.0 - 17.7%). Overall survival (OS), progression-free survival (PFS) and PN incidence were not pooled due to lack of reporting and trial heterogeneity. Prognostic factors identified included B2M (PFS) and advanced age (PFS and OS). Overall, thalidomide demonstrated an ORR approaching 30%, with low CR rate of 1.6% and VTE and DDI incidences of 3% and 15%, respectively.