BACKGROUND We present a study of treatment outcome and evaluate pre-treatment prognostic factors in patients treated for low-grade non-Hodgkin's lymphoma (LG-NHL) at our institution during a ten-year period. METHODS 169 consecutively registered patients from 1986 to 1996 were retrospectively analysed with regard to demographic, treatment, and disease-specific characteristics. Median follow-up time was 52 months. All patients were diagnosed histologically according to the previous Kiel classification system. Median age was 60 years; the male:female ratio was 1.05:1. RESULTS The response rate was 66%; median overall survival 8.3 years. Five and ten-year overall survival were 72% and 47% respectively. For stage 1, 2, 3 and 4, ten-year overall survival were 86%, 65%, 33% and 29%. Of the pre-treatment parameters, advanced stage, B-symptoms, poor performance status, bone marrow infiltration, tumour > or = 6 cm, low serum albumin, anaemia, and LD > or = 540 U/l were all related to survival. According to the multivariate analysis, stage, performance status, tumour size, and anaemia were found to be independent prognostic factors for overall survival. CONCLUSIONS The strategy of radiation therapy has proved successful for most patients with stage 1 disease. Independent prognostic factors for overall survival such as stage, performance status, tumour size, and anaemia may be useful guides in deciding when and how to treat.