Some previous studies have documented an increase in lipoprotein (a) [Lp(a)] levels in renal diseases. Here, we report data in subjects with end-stage renal failure treated with hemodialysis (HD) or with continuous ambulatory peritoneal dialysis (CAPD) and in renal transplant recipients (RTR), compared with a group of normolipidemic controls (C). Lp(a) levels were significantly increased in HD and CAPD patients in comparison with C, while they were only slightly increased in RTR. Both HD and CAPD patients showed Lp(a) levels higher than in RTR, but no difference was found between the subjects of the two dialysis procedures. The prevalence of Lp(a) levels > 25 mg/dl was significantly higher in HD and CAPD patients, but not in RTR, in comparison with C. Moreover, Lp(a) levels did not change after HD. When patients were divided according to their fasting lipid levels in normolipidemics and hyperlipoproteinemics, no difference was found for Lp(a) levels in any group. Mechanisms underlying the increase in Lp(a) levels in these patients are not known. It is possible to suggest an active role of the kidney in the Lp(a) metabolism or that uremic plasma contains some factors affecting Lp(a) metabolism.