Consolidation therapy improves the duration of response among patients with primary central nervous system lymphoma (PCNSL). Lenalidomide maintenance has shown encouraging results in older patients with PCNSL. Herein, we performed a retrospective, single-center analysis to evaluate the effect of lenalidomide maintenance on the duration of response in patients with newly-diagnosed PCNSL. Sixty-nine adult patients with PCNSL who achieved complete remission or partial remission (PR) after induction therapy were enrolled. The median age of patients was 58.0 years. The maintenance group (n = 35) received oral lenalidomide (25 mg/day) for 21 days, every 28 days for 24 months; the observation group did not undergo any further treatment. After a median follow-up of 32.6 months, the maintenance group experienced fewer relapse events. However, the median progression-free survival (PFS) was similar between groups (36.1 vs. 30.6 months; hazard ratio, 0.78; 95% confidence interval, 0.446). Lenalidomide maintenance significantly improved PFS and overall survival (OS) only among patients who experienced PR after induction. The median duration of lenalidomide maintenance was 18 months; lenalidomide was well tolerated and minimally impacted the quality of life. The present study was the first to evaluate lenalidomide maintenance as a frontline treatment among patients with PCNSL, PFS and OS did not improve, although the safety profile was satisfactory.