Renal osteodystrophy is a virtually universal complication of chronic renal failure (CRF). Varying degrees of calcium-phosphate metabolism derangement and different types of skeletal damage are observed in CRF for many reasons while the use of dialysis for the management of end-stage renal failure further affects these complications. This study was designed to evaluate the bone mineral density (BMD) that is measured by dual-energy x-ray in three groups of patients: A, 10 patients on continuous ambulatory peritoneal dialysis (CAPD); B, 10 patients on hemodialysis (HD); and C, 10 predialytic patients with advanced CRF. All patients were matched for age, sex, duration of dialysis (> 3 years), and the use of phosphate binders. Biochemical (serum iPTH levels, SAP, Ca, P) and radiological bone studies were compared in the three groups. The majority of predialytic patients had BMD values within the normal range, while the BMD values in PD patients were higher (0.985 g/cm2) in comparison with HD patients (0.949 g/cm2). Some patients, especially in the HD population, showed an increase in BMD with time on dialysis. From all other comparisons, radiological signs of high turnover bone disease and osteopenia were the only variables that were correlated with BMD. All these findings suggest that dialysis affects the bone status and that CAPD patients have better bone mineral metabolism as shown mainly with the use of BMD measurements.