Abstract: Objective To investigate the correlations between serum CA125 level and infiltration of lymphoma cells and response to treatment in patients with non-Hodgkin s lymphoma(NHL). Methods Serum CA125 levels in 103 patients with NHL were measured by radioimmunoassay (RIA),and the associations between CA125 levels and other presenting features were examined. Results CA125 levels were elevated in 49.5% of patients with NHL. A higher CA125 level was associated with high serum lactate dehydrogenase level, bone marrow involvement, ext ranodal involvement, and effusions, bulky disease and high expression of CD20 ( P < 0. 05) . Complete responses were higher in patient s with normal CA125 levels than in patient s with elevated CA125 levels, and the latter patient s were apt to recurrence. Conclusion There are some correlations between serum CA125 level and infilt ration peculiarity of lymphoma cells. And serum CA125 can be taking as an important auxiliary index to diagnose, advanced disease and evaluation the effectiveness of t reatment .