In 144 patients on hemodialysis (76 males and 68 females, median age 55.7 +/- 14.1 years, mean period on dialysis 44.1 +/- 33.3 months), thrombomodulin was determined by enzyme immunoassay prior to initiation of hemodialysis. The results showed that the mean thrombomodulin value of hemodialysis patients was 13.59 +/- 3.63 ng/ml which was significantly higher than the control value (3.20 +/- 0.90 ng/ml). The thrombomodulin values were significantly higher in patients with blood access failure (15.27 +/- 4.45 ng/ml) than in those without (13.11 +/- 3.31 ng/ml), and the rate of blood access failures was also significantly higher in those with thrombomodulin values of 15.0 ng/ml or higher than in those with values < 15.0 ng/ml. It was evident that there is a higher risk of blood access failure in patients with severe systemic vascular endothelial injury, and thrombomodulin is a useful marker of such an injury.