This study aimed to determine the association of vitamin D serum blood levels and vitamin D gene polymorphism with the severity of coronary lesions in patients with stable coronary artery disease (CAD). Material and methods. 260 patients with stable CAD (average age was 58 years) were examined in the presented research. All patients were divided into two groups according to the SYNTAX score: low-risk patients with SYNTAX score ≤ 31 (n = 224) and high-risk patients with SYNTAX score > 31 (n = 36). For enzyme-linked immunosorbent assay and genetic analysis, peripheral blood was collected from the cubital vein into vacuum tubes containing coagulation activator and K3-EDTA, respectively. Serum blood level of 25-hydroxyvitamin D (DiaSource Diagnostics, Belgium) and 1,25-dihydroxyvitamin D (Immunodiagnostic Systems, Great Britain) were determined by enzyme-linked immunosorbent assay according to the manufacturers’ protocols. Genomic DNA was isolated by phenol-chloroform extraction method from whole blood. The quality and quantity of isolated DNA were assessed using NanoDrop spectrophotometer (Thermo Fisher Scientific, USA). Five polymorphic variants in the VDR (rs2228570 and rs73123) and GC (rs7041, rs1155563 and rs2298849) genes were selected for analysis. Genotyping was performed by real-time PCR in a 96-well plate with fluorescently labeled TaqMan probes. The quality of PCR was controlled by repeated genotyping of 10 % of the analyzed samples. Results. We found no statistically significant differences in serum blood level of the studied markers in patients from low-risk and high-risk groups. One polymorphic variant in the GC gene associated with the multiple coronary lesions (rs2298849) (odds ratio 2.26, 95 % confidence interval 1.28–3.99, p = 0.006) according to an additive inheritance model was identified. In addition, we determined the association between low serum blood level of 1,25-dihydroxyvitamin D in patients with CAD with multiple lesions of the coronary vascular system with A/A – A/G genotypes of the rs2228570 polymorphism in the VDR gene, A/A genotype of the rs7041 polymorphism and A/A genotype of the rs2298849 polymorphism in the GC gene. Conclusions. Allelic variants in the vitamin D metabolism genes are associated with the degree of coronary artery lesions assessed by the SYNTAX score in patients with stable CAD. Also, serum blood level of the active form of vitamin D (1,25-dihydroxyvitamin D) is less in carriers of homozygous genotypes for the major alleles of the VDR and GC genes.