The goals of study NHL-BFM 90 for the therapy group Non-B NHL are to prospectively evaluate the dynamic of tumor regression and the persistence of a residual mass after induction therapy for its prognostic impact. Patients (pts) of stages I and II receive induction composed of prednisone, vincristine (VCR), daunorubicin, L-asparaginase (L-ASP), cyclophosphamide (CP), cytarabine (ARA-C), 6-mercaptopurine (6-MP) and intrathecally (i.th.) methotrexate (MTX), followed by consolidation (6-MP,MTX 5 g/m2 x 4, MTX i.th.), and maintenance up to 24 months. Pts of stages III and IV receive additionally reinduction (Dexamethasone, VCR, doxorubicin, L-ASP, CP, ARA-C, 6-thioguanine, MTX i.th.) and cranial irradiation. Pts with < 70% tumor regression at day 33 of induction receive an intensified chemotherapy. Pts with > 70% tumor regression at day 33 but a persistent mass at the end of induction have a surgical resection. Pts with a completely necrotic residual mass continue with consolidation therapy. Pts with active residual lymphoma receive an intensified chemotherapy. No local radiotherapy is given. From 4/1990 to 12/1992, 80 pts were registered; 71 pts are evaluable for response. The distribution of stages is as follows: 6, 1, 47, 17 pts of stage I, II, III, IV, respectively. The probability of event free survival at 3 years is 87 +/- 4% for the whole group (median observation time 21 months). 66 pts are evaluable for the dynamic of response.(ABSTRACT TRUNCATED AT 250 WORDS)