Methylene-tetrahydropholate reductase (MTHFR) represents an important cofactor in homocysteine (Hcy) metabolism, playing a role in the remethylation of Hcy to methyonine. Decreased MTHFR activity is associated with elevated Hcy plasma level, important due to established toxicity of the Hcy to vascular endothelium. MTHFR activity has genetic determination: polymorphisms C677T and A1298C in MTHFR gene cause decreased enzyme activity. Large number of studies analyzed frequencies of these polymorphisms in patients with vascular diseases. These investigations are important for renal transplanted patie nts too, trying to give answers about a role of genetic factors in hyper-Hcy-emia in these patients. The aim of our study was to establish MTHFR C677T and A1298C frequencies in 78 renal transplanted (RT) patients, and to make correlation between genotypes, Hcy plasma levels, biochemical and clinical markers of atherosclerosis. The established frequencies of C677T and A1298C alleles and genotypes in HD patients were not different from that in whole population. Patients with MTHFR 677TT and 1298CC genotypes showed higher Hcy levels but without statistical significance. Both groups had lower thickness of the wall of carotid arteries, compared to the other MTHFR 677 and 1298 genotypes. The results have practical implementation, indicating etiology of hyperhomcysteinemia and possibilities for vascular disorders prevention in nephrological patients.