In an attempt to evaluate natural history, prognostic factors and survival, the data of 340 patients with NHL were collected. 267 patients were evaluable for the analysis of prognostic factors and survival. The tumor samples were reviewed and reclassified according to the Kiel classification. At completion, 180 patients were affected by low-grade (LG)-NHL and 87 patients had high-grade (HG)-NHL. Numerous potential prognostic factors were analysed in univariate and multivariate analyses. Globally 154 patients (57.4%) obtained complete remission (CR) and 65 patients (24.3%) partial remission (PR). The response rate was similar in LG and HG-NHL groups. 5-years survival was 52% for all patients (53% in LG-NHL and 44% in HG-NHL). Median survival was 62 months in LG-NHL and 38 months in HG-NHL (p = n.s.). At the univariate analysis overall survival (OS) in LG-NHL was favourably influenced by age < 65 years (p = 0.004), performance status > 80 (p < 0.02), early clinical stage (p < 0.001), absence of systemic symptoms (p < 0.001), low serum LDH (p < 0.001) and achievement of CR (p < 0.001), while in the HG-NHL only by age (p = 0.005) and achievement of CR (p < 0.001). The multivariate analysis showed early clinical stage, low serum LDH, absence of systemic symptoms and achievement of CR as independent prognostic factors in LG-NHL and only achievement of CR in HG-NHL.(ABSTRACT TRUNCATED AT 250 WORDS)