Osteoprotegerin is a circulating osteoclastogenesis inhibitory factor and serum osteoprotegerin levels are elevated in hemodialysis patients. This study investigated whether osteoprotegerin levels correlated with various clinical parameters in hemodialysis patients. The subjects were 45 men and 37 women aged from 27 to 94 years (mean = 60.4 +/- 13.9 years), and the duration of dialysis was 9-277 months (mean = 89.5 +/- 64.7 months). Serum osteoprotegerin levels were measured by enzyme-linked immunosorbent assay. Data were analyzed by stepwise multiple regression analysis. The mean osteoprotegerin level of the hemodialysis patients was 303 +/- 210 pg/mL, which was higher than in age-matched healthy controls. Osteoprotegerin levels increased with age, a longer duration of dialysis, and the presence of diabetes. Skeletal resistance to parathyroid hormone might be increased by aging, a long dialysis period, and diabetes, perhaps explaining why adynamic bone disease is more common in older or diabetic patients.