The efficacy and safety of acipimox, an antilipolytic agent, were studied in 10 uremic patients under hemodialysis (group A) and in 8 renal transplant recipients with adequate renal function (group B). The medication was given for 20 weeks at a dose of 250 mg daily in both groups. Total serum cholesterol decreased significantly from 218.1 +/- 17.4 to 175.2 +/- 15.2 mg/dL (-19.7%) in group A and from 261.2 +/- 16.5 to 215.3 +/- 26.9 mg/dL (-17.6%) in group B; as did serum triglycerides, from 206.7 +/- 26.9 to 146.9 +/- 17.6 mg/dL (-29%) in group A and from 168.2 +/- 20.6 to 111.3 +/- 12.4 mg/dL (-33.8%) in group B. Low-density lipoprotein (LDL)-cholesterol and very low-density lipoprotein (VLDL)-cholesterol were also decreased significantly (LDL-C by -27% and -25%, and VLDL-C by -29.2% and -33.8% in groups A and B, respectively). Furthermore, the high-density lipoprotein (HDL)-cholesterol was increased significantly, by +29.6% in group A and +18% in group B. The apolipoproteins Apo-A1 and Apo-A2 were decreased in Group A but not in group B. The Apo-B was decreased in group B. Serum CPK (total and muscle fraction), total bilirubin, SGPT, SGOT, alkaline phosphatase, gamma GT, LDL, a-Fp, and creatinine remained unchanged in both groups. Acipimox seems to be effective in the regulation of atherogenic lipid disorders in hemodialysis patients and renal transplant recipients, without any muscular damage or alteration of kidney and liver function.