Objective To explore the effect of Bacillus Calmette guerin vaccine (BCG) on apoptosis of lymphocytes in asthmatic BALC/c mice Methods Asthmatic BALB/c mice model established by inhaling ovalbumin was treated by BCG Lymphocytes apopotic index and DNA damage index were determined by comet method and xylidine method,respectively Results Apoptosis index and DNA damage percentage of peripheral blood and BALF lymphocytes were significantly elevated after BCG treatment( P