The objective of the present case-control study was to measure blood homocysteine (HC) levels in 215 patients at the age from 20 to 69 years presenting with confirmed venous thrombosis and pulmonary embolism (PE). The control group was comprised of 156 subjects aged between 20 and 67 years. The former group (mean age 40.3 years) consisted of 114 (53%) mean (men age 41.0 years) and 101 (47%) women (mean age 39.4 years). The upper serum HC level for the residents of Western Siberia was assumed to be 11.0 mcmol/l (=9.6±2 SD). The mean serum HC level in the patients of the study and control groups was 13.81±0.52 and 9.95±0.47 mcmol/l respectively (p<0.001). Hyperhomocysteinemia (HHC) was documented in 80.5% of the patients with venous thrombosis and PE compared with 18.6% among the controls (p<0.001). The mean serum HC level in the men of group 1 was 14.74±0.8 mcmol/l versus 12.76±0.6 mcmol/l in the women (p<0.001). The odds ratio (OR) characterizing the relative risk of development of venous thromboembolic complication (VTEC), taking into consideration the serum HC levels, increased on the whole by 1.7-2.0 times (1.9-2.7 and 1.4-1.5 times in men and women respectively). HHC in the patients aged 45 years and below increased OR for the development of VTE by 2.0-2.6 times depending on the blood HC level (2.1-4.2 and 1.6-1.7 times in men and women respectively). HHC in the patients aged above 45 years, increased OR for the development of VTEC by 2.5-3.8 times depending on the blood HC level (2.7-4.2 and 2.1-4.2 times in men and women respectively). It is concluded that hyperhomocysteinemia is an independent risk factor of VTE in the residents of Western Siberia. The relative risk of development of VTE in the patients presenting with HHC increases with age (more significantly in men than in women).