Small noncleaved cell lymphoma (SNCCL), a rare lymphoma in adults, is associated with not only a rapid complete response (CR) to chemotherapy but also with the potential to rapidly relapse both systemically and in the CNS. We treated 44 assessable adults with two similar protocols, consisting of three sequential chemotherapy combinations and intrathecal prophylaxis with methotrexate and cytarabine. The overall CR rate was 80%; it was 100% in patients with Ann Arbor (AA) stages I-III disease and 57% in those with stage IV disease. The overall survival (OS) rate at 5 years was 52%. The overall 5-year freedom from tumor mortality (FTM) rate was 63%; it was 95% for patients with AA stages I-III disease, and 29% for those with stage IV disease. Stepwise multivariate analysis of factors associated with remission duration and survival indicated that advanced-disease stage and age of 40 years or over were predictors of poor prognosis. Twelve patients with positive human immunodeficiency virus (HIV) serology were also included in this series. They had an 83% CR rate and an 83% 5-year FTM, but only a 36% 5-year OS; most deaths were secondary to opportunistic infection. Histologic subtype (Burkitt's lymphoma [BL] or non-Burkitt's lymphoma [NBL]) did not correlate with patient age, site of tumor presentation, response to therapy, or survival. Both protocols achieved comparable results. The approach used in these protocols is highly effective for patients with early staged disease, regardless of their HIV status; however, better therapy is necessary for those with SNCCL presenting in an advanced stage.