From 1983 to 1988, non-Hodgkin's lymphoma was diagnosed in 169 patients ranging from 19 to 89 years of age (mean 49). They were investigated using both unifactorial and multivariate regression (Cox model) analyses to determine the relationship of survival rate and prognostic factors including age, sex, histology, B symptom and clinical stage. All cases were histologically classified according to the criteria of the working formulation and were staged according to the Ann Arbor classification. Non-Hodgkin's lymphoma occurred roughly 9 times as frequently as Hodgkin's disease. The lymph nodes of the neck and inguinal regions were noted to be the most common sites of involvement. However, extranodal lymphomas originated most frequently from the stomach. For the patients with non-Hodgkin's lymphoma, the proportions of low grade, intermediate grade, and high grade were 10.7%, 59.1% and 20.7%, respectively. The remaining 9.5% of cases were unclassified (7.7%) and true histiocytic (1.8%). The most common subtype was diffuse large cell (33.7%). Lymphoblastic lymphoma was found to have a predilection for young male adults. Follicular lymphomas occurred mainly in mid-adult life. The patients with high grade lymphoma almost always presented the advanced stage. The median survival time (MST) of our series was 20 months, the 3-year survival rate was 43.3% and the 5-year survival rate was 30.40%. Statistical studies of both unifactorial (p less than 0.01) and multivariate regression (p less than 0.05) analyses showed that patients with an age greater than 60 years old, having B symptom, clinically advanced stage, or both histologically intermediate and high grade experienced a much poorer prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)