In order to study relationship between development of idiopathic atrioventricular (AV) and intraventricular disorders of cardiac conduction (DCC) with single nucleotide polymorphism (SNP) of TBX5 gene we examined 260 persons with primary DCC (71 patients with abnormal AV conduction, 84 and 105 patients with disordered conduction along right and left brunches of His bundle, respectively) as well as 257 individuals without cardiovascular diseases (control group). Patients were divided into subgroups depending on nosology, age, and sex. Diagnosis was verified by standard cardiological methods and retrospective analysis of available results of previous examinations. Molecular-genetic study of DNA was used for identification of genotype of TBX5 gene SNP. The results indicated significant preponderance of rare GG genotype (CNP-marker rs3825214) of TBX5 gene in the group of patients with left bundle branch block and in the subgroup of women with this pathology. These data suggest that presence of GG genotype (rs3825214) of TBX5 gene increases probability of development of idiopathic DCC along left bundle branch mainly in women.