Serum uric acid (SUA) but also hemorheological parameters such as hematocrit (Hct) and whole blood viscosity (WBV) are markers of cardiovascular risk. Increased blood cell volume is one of the known causes of hyperuricemia. We therefore aimed to investigate the relationship between SUA and hemorheology in untreated borderline hypertensive young men (n = 67) and in subjects with established hypertension and left ventricular hypertrophy (n = 40) examined when they had been without treatment for 2 weeks. We found positive correlations between SUA and Hct (r = 0.46, p < 0.0001), hemoglobin (Hgb) (r = 0.40, p = 0.001), mean blood pressure (BP) (r = 0.39, p = 0.001) and body weight (r = 0.26, p = 0.036) in the borderline hypertensive young men. No relation between SUA and glucose disposal rate (GDR) assessed with hyperinsulinemic isoglycemic glucose clamp appeared (r = -0.06, p = 0.633). Multiple regression analysis showed that 33% of the variation in SUA could be explained by BP and Hct. We also found positive correlations between SUA and Hgb (r = 0.40, p = 0.011) and body weight (r = 0.42, p = 0.006) and an inverse trend with GDR (r = -0.27, p = 0.087) in the subjects with established hypertension. Multiple regression showed that 32% of the variation in SUA was explained by Hgb and body weight. These data suggest that hemorheology may be involved in the uric acid metabolism in borderline as well as in established hypertensives. Hemorheology may possibly be a link between SUA and cardiovascular risk. There was no relation between SUA and insulin resistance in these hypertensive groups.