The association of the T894G endothelial nitric oxide synthase (eNOS) gene polymorphism with certain indicators of endothelial function in patients with hypothyroidism and concomitant chronic non-calculous cholecystitis was investigated. Significant increase by 33.1 % (P = 0.01) of desquamated endothelial cells number in the blood was found in patients with T-allele compared with that of in GG-genotype carriers. Also, the concentration of total nitric oxide stable metabolites was 10.4 % (P = 0.04) higher and the level of nitrate anions in the blood was 10.8 % (P = 0.02) higher than in comparison group. Among patients with hypothyroidism and concomitant chronic cholecystitis, the content of vascular endothelial growth factor was 27.7 % (P = 0.03) higher in T-allele carriers as compared with patients with GG-genotype.