We evaluated early intensification followed by autologous bone marrow transplantation (ABMT) using marrow purged by mafosfamide in patients with high-risk low-grade follicular lymphoma (LGFL) reaching a status of minimal disease (MD). Thirty-four patients entered the program. All fulfilled at least one of the following criteria at diagnosis: a bulky tumor > 7 cm; three or more adenopathies > 3 cm; massive pleural or peritoneal effusion; massive splenomegaly; B symptoms; platelet count < 100 x 10(9)/l. Twenty-one patients had bone marrow involvement. Twenty-six patients received ACVBP, and eight CVP as front-line therapy. Twenty-one (62%) patients achieved MD status, 18 reached intensification. At 4 years, the time to treatment failure is 55 +/- 9%, and the probability of persisting remission is 75 +/- 11%. Comparison by intention to treat of the 26 patients who received ACVBP as front-line therapy to 14 historical high-risk LGFL similarly treated in our institution without intensification, showed better results for the intensified group (P = 0.04 for both probability of persisting remission and time to treatment failure). These results indicate that early intensification using marrow purged with mafosfamide is a therapeutic option which may bring benefit to patients with high-risk LGFL.