The polymorphism of the TNF A gene was studied in 89 asthmatic patients and their 162 relatives in order to estimate the contribution of this candidate gene to the predisposition to the development of asthma and allergic diseases. A control group comprised 258 individuals without bronchopulmonary pathology The polymerase chain reaction was used to study the 308 G/A polymorphism of the TNF A gene. The findings suggest that the asthmatic patients and their relatives have no association of the polymorphism of the TNF A gene in position 308 with their predisposition to the disease. Analysis of the distribution of the frequencies of alleles and genotypes among their probands, relatives, and the control group revealed no statistically significant differences between the groups.