To assess lymphocyte subsets and expression of activation antigens in peripheral blood lymphocytes (PBLs) in chronic alcoholism, a cross-sectional study with 30 well-nourished chronic alcoholics and 30 controls was performed. Studies included detailed clinical and laboratory evaluation, nutritional status assessment, and determination of lymphocyte subpopulations, as well as activation antigens. A significant decrease of B cells (CD19+) was observed in chronic alcoholics, compared with controls (p < 0.001). A significant increase of PBLs expressing CD69 and CD25 (p < 0.01, both) in chronic alcoholics was also detected, whereas CD71 expression was unaffected. In addition, T lymphocytes expressing HLA-DR were significantly higher in chronic alcoholics than controls (p < 0.05). The serum level of soluble interleukin-2 receptor was also significantly higher in the alcoholic group, compared with controls (p = 0.04). Moreover, the estimated total lifetime dose of ethanol consumed correlated positively with the percentage of PBLs expressing CD25 (r = 0.48; p = 0.01) and negatively with PBLs expressing CD71 (r = -0.39; p = 0.04). By contrast, the changes were not related to age, nutritional status, or the presence of other ethanol-related diseases. In conclusion, chronic alcoholics present a significant decrease of B cells and an "incomplete activation state" of PBLs that depends on the dose of ethanol consumed.