Disintegrin and metalloprotease 33 (ADAM33) have been associated with childhood and adult asthma in many populations. ADAM33 mutations might predispose to altered lung function in early infancy. In this study, we investigated the association between single-nucleotide polymorphisms in ADAM33 and the incidence of adult and childhood asthma among Jordanians. One hundred seven pediatric asthmatic patients, 115 healthy pediatric patient controls, 160 adult asthmatic patients, and 110 healthy adults were enrolled in this study. ADAM33 polymorphisms were genotyped using the polymerase chain reaction/restriction fragment length polymorphism method. A strong association between the V4 genotype and incidence of childhood asthma was found. In the single-locus analyses of asthma risk, V4 C/G single nucleotide polymorphism (SNP) showed a trend toward significance with p=0.07. Interestingly, the CC homozygous mutant genotype frequency was significantly higher in asthmatic subjects (15.9%) than in control subjects (2.6%), resulting in an odds ratio of 7.05. In adult cases, S2, the F+1 and Q-1 genotype showed a significant association (p≤0.05) with the incidence of asthma. Two haplotypes also exhibited a significant association with asthma (p≤0.05). In conclusion, the findings of this study confirm the already reported association between V4 SNP and the incidence of childhood asthma as well as between S2, F+1, and Q-1 SNPs and the incidence of adult asthma in several populations.