A prospective randomized clinical trial with simultaneous data collection for an economic appraisal was carried out to assess the effectiveness, quality of life and cost implications of ABMT vs standard chemotherapy in slowly responding patients with intermediate- and high-grade malignant non-Hodgkin's lymphoma (NHL). The patients had a partial response after three cycles of chemotherapy and had no evidence of BM involvement of NHL. The overall and disease-free survival at 3 years were 61% and 60%, respectively, in the ABMT group and 85% and 77% in the CHOP group (P = NS). Moreover, there were more (severe) complications and symptoms in the ABMT than in the CHOP group. The average costs of CHOP chemotherapy were significantly lower than the average costs in the ABMT group (CHOP: US$ 3118 vs ABMT: US$ 34,447). Considering long-term consequences the ABMT group was more expensive (US$ 34,580) and patients experienced 0.14 life years and 0.22 quality adjusted life years less than the CHOP group (discount rate 5%). As a result, changing therapy from CHOP to ABMT, as primary treatment in slow responders to CHOP, can not be recommended as the required additional investment does not produce health gains in terms of survival or quality of life.