Purpose To assess potential benefits with thalidomide incorporated into double autologous stem-cell transplantation (ASCT) for younger patients with newly diagnosed multiple myeloma (MM). Patients and Methods One hundred thirty-five patients who received thalidomide from induction until the second ASCT were retrospectively analyzed in comparison with an equal number of pair mates treated with double ASCT not including thalidomide. Results On an intention-to-treat basis, the addition of thalidomide to double ASCT effected a significant improvement in the rate (68% v 49%; P = .001) and duration (62% v 33% at 4 years; P < .001) of at least very good partial response (VGPR), time to progression (TTP; 61% v 41% at 4 years; P < .001) and progression-free survival (PFS; 51% v 31% at 4 years; P = .001). A trend was also noted for extended overall survival (OS) among thalidomide-treated patients (69% at 5 years v 53% for the control group), although the difference between the two groups was not statistically significant (P = .07). Benefits with thalidomide in increasing the rate of VGPR or better response, TTP, and PFS were confirmed in a multivariate analysis. Median OS after relapse was 24 months for patients receiving thalidomide added to double ASCT and 25 months for the control group. Overall, 17% of patients discontinued thalidomide, including 8% because of drug-related adverse events. Conclusion In comparison with double ASCT, the addition of first-line thalidomide to double ASCT improved clinical outcomes. Short-term thalidomide was generally well tolerated and had no adverse impact on postrelapse survival.