Association of the methylenetetrahydrofolate reductase gene (MTHFR) C677T missense mutation (substitution of cytosine by thymine at position 677) with coronary artery disease (CAD), as well as with blood levels of various lipoprotein fractions, systolic pressure (SP), diastolic arterial blood pressures (DP), and body mass index (BMI) in patients with angiographically verified CAD and in a control group. The affected and control subjects did not differ substantially with respect to genotypic and allelic frequencies. The MTHFR gene polymorphism was not associated with variation in either total cholesterol (TC), very-low-density-lipoprotein cholesterol (VLDLC), low-density-lipoprotein cholesterol (LDLC), high-density-lipoprotein cholesterol (HDLC), or triglyceride (TG) levels. SP and DP in subjects with different MTHFR genotypes did not differ significantly. BMI tended to correlate with the C677T polymorphism of the MTHFR gene (0.05 < P < 0.1). C677T mutation frequencies in western Siberia were determined for the first time; they are about the same as in most European populations.