BACKGROUND The late effects of chemotherapy of aggressive non-Hodgkin's lymphoma on gonadal function are largely unknown. METHODS In a retrospective study the gonadal function after chemotherapy with MACOP-B or VACOP-B with or without dose intensification and ABMT in first remission was examined in patients with aggressive non-Hodgkin's lymphoma by patient history and determination of hormonal function. Thirty adult patients of age 40 or less at diagnosis who were alive and free of relapse for at least 1 year after completion of chemotherapy were included in the study. RESULTS With a median time of 28 months (range 11 to 62 months) after completion of therapy, gonadal dysfunction was found in 1 of 7 female and none of 15 male patients, or a total of 5% of patients treated with chemotherapy alone. Of patients receiving dose intensification and ABMT in first remission, gonadal dysfunction was present in 2/6 (33%) treated with cyclophosphamide, BCNU and etoposide in 3/4 treated with cyclophosphamide and TBI. CONCLUSIONS Our data suggest that therapy of aggressive non-Hodgkin's lymphomas with MACOP-B or VACOP-B has little impact on future fertility and that fertility may be preserved in the majority of patients receiving dose-intensification with CBV in first remission.