ABO is the most important blood group system in transfusion and transplantation practices. Glycosyltransferases are controlled by the ABO system which is helpful in building oligosaccharide structures on the cell surface of erythrocytes and vascular endothelium and in the exocrine secretion system, including the respiratory tract. We analyzed the ABO blood group of 200 children and adults with asthma as well as that of 2000 healthy subjects as controls. The most common blood group among the patients and controls was "O" (43.5% and 43.6%, respectively), followed by B, A, and AB. In the distribution of different blood groups, nonsignificant difference between patients and controls was observed (p = 0.931). We conclude that ABO blood group status has a nonsignificant association with asthma among the population of Mysore, Karnataka, South India.