This prospective study was undertaken to evaluate the efficacy and toxicity of combination chemotherapy with alternating cycles of vincristine, doxorubicin and dexamethasone (VAD) and cyclophophamide, doxorubicin, etoposide and prednisone (CHEP) in patients over 60 years old with previously untreated and advanced non-Hodgkin's lymphoma (NHL) of intermediate- and high-grade malignancy. Eighty one consecutive, patients with NHL referred from April 1992 to October 1997 to GOELAMS centers were enrolled in this study and their outcome updated to June 1, 1999. Of 81 enrolled patients, 77 were eligible and assessable for response. The median age was 70 years (61 to 78), 85.7% were stage III or IV, 39% were of performance status > or = 2, 27.3% > or = 2 involved extra-nodal sites and 57.3% had higher LDH levels than normal. The immunophenotype was B in 87% and T in 13%. Fifty-one (66.2%) patients received the scheduled eight cycles of therapy and treatment was withdrawn in only 6 patients (7.8%) because of toxicity. Neutropenia grade 3-4 occurred in 11.1% after VAD courses vs 40.6% after CHEP courses. The mean cumulative dose of doxorubicin was 269 mg/m2 and the relative dose intensity was 84%. The overall response and complete response rates were 66.2% and 51.9% respectively, and after a median follow-up of 52 months the 3 year overall survival (OS) and event-free survival rates (EFS) were 43.5% and 33.0% respectively. In multivariate analysis, OS and EFS were statistically influenced by IPI (p = 3 x 10(-3); p < 1 x 10(-4)) and phenotype (p = 2 x 10(-3); p < 1 x 10(-4)). Our findings support the alternation of 4 courses of VAD and CHEP as it is well tolerated in patients over 60 years old with advanced intermediate- or high-grade NHL and provides response and survival rates comparable to 6 courses of CHOP.