During 1980-1983, two major advances were made in the treatment of Burkitt's lymphoma (BL): conventional but aggressive chemotherapy raised the overall survival rate from 42% with the SFOP1 protocol, COPAD, to 80% with SFOP protocols LMB 01 and 02; and massive chemotherapy followed by autologous bone-marrow transplantation (ABMT) enabled 40% of relapses to be cured. Ten patients included in the COPAD protocol were treated with massive therapy: seven because of relapse, one because of partial remission after two months' induction therapy and two because of long delay before first complete remission (CR). The therapy used was bischloroethyl nitrosourea, cytosine arabinoside, cyclophosphamide (CPM) and 6-thioguanine (BACT) in nine cases and CPM in one. The response rate was 100%, and disease-free survival was reached in five of ten cases, including four with no evidence of disease for over two years. In nine of ten patients who received ABMT, the bone marrow (BM) was not decontaminated, and BM involvement was found at death prior to day 86 from ABMT in four of five failures. Clinical and cytological analyses led to no firm conclusion about the role, if any, of reinjected BM in this outcome: a liquid-culture monitoring system used in six cases showed BM malignant cells present in the graft in one early relapse and absent in two relapses in which BACT failed; in three long-term survivors, no malignant cell was found in the graft. This first group of ten showed the efficiency of BACT and the necessity of purging BM in at least some cases before ABMT. Of the second group, selected from 43 patients given LMB 01 and 02 protocols, eight were treated by massive therapy and ABMT: one with localized stages I and II disease, four with stage III and three with stage IV. These patients received massive therapy either because of early relapse, progressive disease, partial remission after induction therapy or long delay before CR, or as a consolidation of CR in cases of central nervous system or cerebrospinal fluid involvement. In this group, four of eight are disease-free; three of them had normal BM by in-vitro liquid-culture monitoring; their BM was not decontaminated and they had no BM relapses. In the other five cases, BM was decontaminated by Asta Z in one and by y-29/55 antibody in four.(ABSTRACT TRUNCATED AT 400 WORDS)