The present study was undertaken to explore the effect of administration of high doses of sodium selenite on the expression of Bcl-2 in patients with non-Hodgkin's lymphoma (NHL). Fifty patients with newly diagnosed NHL were randomly divided into two groups. Group A-I received standard chemotherapy whereas group A-II received adjuvant sodium selenite 0.2 mg kg-1 day-1 for 30 days in addition to chemotherapy. Enzyme-linked immunosorbent assay was used to assess Bcl-2 at the time of diagnosis and after therapy in the two groups. Sodium selenite administration resulted in significant decline of Bcl-2 level after therapy in group A-II (8.6 +/- 6.9 ng/ml vs 3 6.9 +/- 7.9 ng/ml, P < 0.05). Also, complete response reached 60% in group A-II compared to 40% in group A-I. Significant increase in CD4/CD8 ratio was noticed in group A-II compared to group A-I after therapy (1.45 +/- 0.36 vs 1.10 +/- 0.28 p 0.04). Overall survival time in months was significantly longer in complete remission patients in group A-II (21.87 +/- 1.41) compared to group A-I (19.70 +/- 1.95) (p = 0.01). It is concluded that sodium selenite administration at the dosage and duration chosen acts as a down regulator of Bcl-2 and improves clinical outcome.