Failure after first-line treatment was reported in 35-60% of immunocompetent patients with primary central nervous system lymphoma (PCNSL). There are currently no reports focusing on salvage therapy. This review analyses prognostic factors and the efficacy of salvage therapy by focusing on data from papers reporting results of first-line treatment in 355 cases. The study group consisted of 173 patients presenting treatment failure. The interval between failure and death (TTD) was compared for age at relapse (< or =60 vs. >60 years), type of failure (relapse vs. progression), time to relapse (< or =12 vs. >12 months) and salvage treatment (yes vs no). Median TTD was similar in younger and older patients (P = 0.09). Relapsed patients had a longer TTD than patients with progressive disease (P = 0.002). Early relapse led to a shorter TTD than late relapse (P = 0.005). Median TTD was 14 months for patients who underwent salvage therapy and 2 months for untreated cases (P<0.00001). A multivariate analysis showed an independent prognostic role for salvage therapy and time to relapse. Age and type of failure had no predictive value. Salvage therapy significantly improves outcome and, possibly, quality of life. As many different treatments were used conclusions cannot be made regarding an optimal treatment schedule.