Abstract： Objective To detect the distribution frequency of different genotypes and alleles of a disintegrin and metalloprotease 33 (ADAM33) polymorphism T1 in children of Han ethnicity in Guangzhou district,and to analyze the association of polymorphism T1 with bronchiolitis.Methods A total of 60 children with bronchiolitis and 60 healthy controls were screened for genotypes by PCR-RFLP.Results The genotype frequencies ofTT,TC and CC at ADAM33 T1 locus were 78.3％,16.7％ and 5％ in patients,while their genotype frequencies were 88.3 ％、10％ and 1.7 ％ in controls.There was no significant difference between patients and controls (X2=2.36,P＞0.05).The allele frequencies of T and C were 86.7％ and 13.3％ in patients,while allele frequencies were 93.3％ and 6.7％ in controls.There was no significant difference between these two groups either (x2=2.27,P＞0.05).Conclusions The results suggest ADAM33 polymorphism T1 is not associated with bronchiolitis in children of Guangzhou district.