Since the early 1970s, three generations of combination chemotherapy for intermediate-grade non-Hodgkin's lymphomas (NHL) have been developed. One of the third-generation regimens is MACOP-B (methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin). The VACOP-B regimen is a modification of MACOP-B in which methotrexate is omitted and etoposide is added. This study assesses treatment outcome using the MACOP-B and VACOP-B combination chemotherapy in a population of young patients with intermediate-grade NHL treated in a single tertiary hematological center. The files of 45 patients aged 18-55 who were diagnosed as having intermediate-grade NHL (working formulation types F-H) and treated between January 1986 and March 1994 were reviewed. Treatment response, overall survival, disease-free survival and treatment toxicity were determined. The predictive value of the age-adjusted international prognostic index was also assessed. Median follow-up was 80 months in the MACOP-B group and 29 months in the VACOP-B group. The complete response rate was 71% (95% confidence interval CI: 58-84), 4-year overall survival was 74 +/- 7% and 4-year disease-free survival was 79 +/- 8%. No toxicity-related deaths were observed. The main adverse effects were WHO grade 3 or 4 neutropenia (51%), anemia (24%) and mucositis (20%). Only the CR rate was correlated with the Age-Adjusted International Prognostic Index. Mean relative dose intensity was high (95.7%, 95%) CI: 91.7-99.7) and had no correlation with treatment outcome. The MACOP-B and VACOP-B combination chemotherapy regimens were found to be effective and minimally toxic for young patients up to 55 years old with intermediate-grade NHL.