We aimed to investigate the polymorphism of T1, T2, V4, S2 sites of ADAM33 gene and to discuss the relationship between ADAM33 gene polymorphism and bronchial asthma in Han population in Inner Mongolia. Restriction fragment length polymorphism (PCR-RFLP) was used to detect ADAM33 gene polymorphism. 178 patients with asthma of Han population were randomly selected, and 195 healthy individuals of the same population were used as controls. The patients were divided into mild, medium and severe group according to the state of attack to analyze the correlation of illness state to genotype.Three genotypes were detected at each of the 4 sites. Compared with the controls, there were no statistical difference in the frequencies of phenotype and genotype at T2 and V4 sites (P > 0.05), whereas there were significant differences at T1 and S2 sites (P < 0.05). There were no correlation between the distribution of genotype and illness severity (P < 0.05). These findings suggest the polymorphism of T1 and S2 loci in ADAM33 gene may play a role in asthma in Han population in Inner Mongolia, but V4 and T2 polymorphisms may not be related to asthma in Han population in Inner Mongolia. Genetic polymorphisms of ADAM33 gene may be irrelevant to the severity of asthma.