Background: In patients diagnosed with calcific aortic valve stenosis, cardiac risk factors are similar to those of coronary artery disease; homocysteine concentration is an independent risk factor for coronary artery disease. The aim of this study was to investigate the correlation between plasma homocysteine levels and aortic valve stenosis and the influence of homocysteine levels on the coexistence of coronary artery disease in patients with moderate to severe aortic valve stenosis. Methods: Fifty-eight patients who had been diagnosed with moderate to severe aortic stenosis formed the test group of this study, and 47 healthy subjects without coronary artery disease or aortic valve stenosis formed the control group. The patients with aortic stenosis were divided into two groups according to the presence or absence of coronary artery disease in their coronary angiograms. After 12 h fasting venous blood samples were collected and total cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides and homocysteine levels were measured and compared between the two groups. Measurements and Results: The mean blood homocysteine level was 10.8 ± 3.3 µmol/l in patients with aortic valve stenosis and 8.1 ± 4.7 µmol/l in the control group; the difference between these levels was statistically insignificant. The patients with aortic valve stenosis had significantly higher levels of total cholesterol and hypertension and were more likely to have a positive family history for coronary artery disease. When the two subgroups of patients with aortic valve stenosis were compared, mean blood homocysteine levels were 13.2 ± 3.1 and 8.3 ± 2.2 µmol/l, respectively, showing significantly higher levels in the group with coronary artery disease. In this comparison patients with coronary artery disease were also found to have significantly higher levels of total cholesterol and LDL and they were more likely to be smokers. Conclusions: Although there was no relation between blood homocysteine levels and the existence of aortic valve stenosis, in cases with both coronary heart disease and aortic stenosis homocysteine levels were significantly higher than in the patients with pure aortic valve stenosis.