The suggested potential long-term use of aspirin for protection against cardiovascular disease and some type of cancer requires further research for understanding mechanisms of aspirin action including its side effects. There are contradictory data concerning effects of aspirin on humoral and cellular immunity. Earlier, we found that lysine-acetylsalicylate(100 mg/kg/d for five days ip), produced significant decrease in the number of spleen PFC against SRBC in guinea-pigs. In this work we studied effects of aspirin on the number of blood large granular lymphocytes (LGL), spontaneous E- rosetting cells with rabbit red blood cells(RRBC),and blood T-lymphocytes(the number of E-rosetting cells minus the number of LGL) in guinea-pigs. The experimental group received lysine-acetylsalicylate in a dose of 100 mg/kg/d, 5d, ip. The control group received 0.9% NaCl. On the sixth day the numbers of blood LGL, blood E-rosetting cells (CD2+ cells), and blood T-lymphocytes were determined. Lysine-acetylsalicylate produced statistically significant increase in the number of blood E-rosetting cells (p<0.05) and blood T-lymphocytes (p<0.05) in guinea-pigs, in comparison with the control group of animals; however, the number of blood LGL was not significantly changed. The results suggest that in certain doses aspirin could enhance proliferative capacity of blood T-lymphocytes without changing the number of blood NK cells.