To determine the immunotoxicological profile of highly contaminated St. Lawrence beluga whales compared to much less contaminated Arctic belugas, various normal immune functions of wild belugas captured in Churchill, Manitoba, were established using peripheral blood leucocytes. Phagocytosis of neutrophils was evaluated by flow cytometry and was found to be maximum after 18 hours of incubation with latex beads. The respiratory burst of the same cells, also evaluated by flow cytometry, was at its maximum 60 minutes after stimulation with PMA. Phenotypic characterization of peripheral blood lymphocytes was performed with bovine and human monoclonal antibodies, using flow cytometry. More than 95 % of these cells reacted positively with MHC class I and II antibodies. While 98% of the lymphocytes were positive for CD2, a T cell marker, only 31% were positive for TCR (yo), and 29% were positive for CD4. The specificity of these reactions is currently under study. Mitogen induced lymphoblastic transformation showed higher reactivity with Con A and PHA than with LPS and PWM. NK function was more pronounced against K-562, a human erythroid cell line, than against YAC cells, a murine lymphoid cell line. The qualitative and quantitative evaluation of the serum immunoglobulins is currently under evaluation.