Intensive chemoradiotherapy, with or without additional local radiotherapy, and unpurged autologous marrow transplantation was given to 68 patients with progressive non-Hodgkin's lymphoma. Responses were attained in 44 patients (65%, 95% confidence intervals [CI], 52% to 76%), including 37 who achieved complete responses. Fifteen patients (22%, 95% C.I. 13% to 34%) remain free of disease (including 11 continuously) at a median of 5.3 (range 3.1 to 9.1) years later. Higher Karnofsky scores (P less than .01, Mann-Whitney U test) and the absence of a history of prior radiotherapy (P = .02, chi 2 test) were associated with achievement of complete plus partial responses. Higher Karnofsky scores (P less than .01, Mann-Whitney U test) and less resistant disease status at transplantation (P = .04, chi 2 test) were significant when calculations were limited to complete responses. Karnofsky scores were also associated with the probability of freedom from progression (P = .02, log-rank) for responding patients. Also, Karnofsky scores and the absence of prior radiotherapy (P less than .01 and P = .01, respectively, log-rank) were associated with improved survival. Progressive lymphoma was the chief cause of failure; progression usually occurred less than 6 months after transplantation, most often at the sites of active disease before the transplant. However, five patients (including four with high-grade non-Hodgkin's lymphoma) suffered hematogenous patterns of relapse; four of these five patients had no prior history of marrow involvement. Other causes of mortality included interstitial pneumonitis, sepsis, hemorrhage and renal failure. Intensive chemoradiotherapy and autologous marrow transplantation produces durable remissions in some patients with progressive non-Hodgkin's lymphoma. Since such therapy is more effective when given to patients with signs of less advanced disease, earlier treatment would be the simplest way to produce improved results. However, improved conditioning regimens will also be needed, and measures to reduce occult lymphoma stem cell contamination with the autograft may also be required to increase the likelihood of cure in some patients.