OBJECTIVE All low-grade non-Hodgkin's lymphoma (LG-NHL) patients diagnosed and/or treated at our institution over a 10 year period were investigated with regard to treatment outcome and possible pre-treatment prognostic factors. METHODS During the period 1986-1995, 169 consecutively registered patients with LG-NHL were retrospectively analyzed with regard to personal, treatment, and disease- specific characteristics. The median follow-up time was 52 months (5-132 months). All patients were diagnosed histologically according to the Keil classification system. Median age was 60 years (range 27-87 years), and the male:female ratio was 1.05: 1. RESULTS The overall response rate was 77%, of which 66% were complete response (CR) and 11% partial response (PR). 5- and 10-year overall survival were 72% and 47%, respectively, and median overall survival was 8.3 years. 10-year overall survival for stage I, II, III, and IV were 86%, 65%, 33%, and 29%, respectively. For follicular lymphoma, 10-year survival was 52% and median survival 12.5 years. In univariate analysis, the following pre-treatment factors indicated a poor prognosis: advanced stage, general symptoms, bone marrow infiltration, poor performance status, tumor > or = 6 cm, low serum albumin, anaemia, and LDH > or = 540 U/l. In multivariate analysis, stage, performance status, tumor size, and anaemia were found to be independent prognostic factors for overall survival. CONCLUSIONS The treatment strategy has proved successful for most patients with localised disease. Independent prognostic indicators for survival as stage, performance status, tumor size, and anaemia may be useful guides in deciding when and how to treat.