The objective of study was to investigate the association between the Gln27Glu polymorphism in the β2-АR gene and body mass index in patients with bronchial asthma with regard to the age of onset. Study included 553 patients with bronchial asthma (BA) and 95 apparently healthy individuals with no individual and family history of asthma symptoms. All of them had previously signed an informed consent form for study participation. The patients were divided into 2 clinical groups depending on the age of BA onset. Group I included 282 patients with late-onset asthma (late-onset asthma phenotype), and Group II included 271 patients with early-onset asthma (early-onset asthma phenotype). There was no significant difference in gender, age, severity, or control level between the groups (р>0.05). BA diagnosis and BA severity were determined according to the GINA recommendations-2016 and its later version. Obesity was diagnosed in accordance with the Order of the Ministry of Health of Ukraine № 574 dated 05.08.2009 and the WHO recommendations (1999), the European Association for the Study of Obesity (EASO, 2016). The Gln27Glu polymorphism in the β2-АR gene (rs1042714) was determined using polymerase chain reaction-restriction fragment length polymorphism analysis. The obtained results were statistically analyzed using SPSS-17 program. No significant difference was established in the distribution of alleles and genotypes for the Gln27Glu polymorphism in the β2-adrenergic receptor gene depending on body mass index (BMI), p=0.1. Obesity relative risk estimation showed a statistically significant correlation related to the dominant (p=0.03) and additive (p=0.04) models of inheritance. The risk of obesity in minor allele carriers (Glu/Glu+Gln/Glu) was 1.75 times higher than that in the major allele homozygotes (р=0.03). No association was observed between the Gln27Glu polymorphism in the β2-AR gene and obesity risk in patients with early-onset bronchial asthma in any model of inheritance. Obesity relative risk estimation in late-onset BA patients showed a statistically significant correlation related to the dominant (p=0.03) and additive (p = 0.001) models of inheritance. The minor allele carriers (Gln/Glu and Glu/Glu genotypes) with late-onset BA had a 1.95 times higher risk of obesity in the dominant model and 1.65 times higher risk of obesity in the additive model vs. the major allele homozygotes. The obtained data indicated that the minor allele carriers of the Gln27Glu polymorphism in the β2-АR gene (both homozygotes and heterozygotes) with late-onset BA had a higher risk of obesity.