The research program outlined in this application is designed to provide a mechanism for randomizing 50-60 patients with progressive renal insufficiency to various dietary protocols. The proposed program will be conducted in the Ambulatory Clinical Research Unit of the Nephrology Section of the Department of Medicine of the Bowman Gray School of Medicine, in Winston-Salem, North Carolina. Patients will be recruited from three clinics: the BGSM private nephrology clinic, a private nephrologist who practices in the community in Winston-Salem, and the Danville Urology Clinic (DUC), a nephrology unit located in Danville, Virginia. Nephrologists at both these latter institutions have clinical faculty appointments at the Bowman Gray School of Medicine. A detailed study of patients in the BGSM clinic has identified 1281 active patients, 470 of whom have renal failure. Sixty-five patients with renal meet all criteria of the MDRD protocol. It is estimated that approximately half of this group of 65 could be recruited into the study, representing a yield of 2.0-2.5% of active patients. Applying somewhat lower yields to the other Winston-Salem clinic and the DUC, we estimate that a total of approximately 58-67 patients can be recruited into the MDRD study. Contingency plans for recruiting patients from four other clinics in the Winston-Salem area are also outlined. The study has four investigators. Three are nephrologists with extensive experience in the care of patients with renal failure. The fourth investigator is an epidemiologist expert in clinical trials and patient compliance. All are on the full-time faculty of the Bowman Gray School of Medicine. The senior dietitian has experience in clinical trials involving dietary intervention. Other key personnel have experience in clinical trials and in techniques needed for assuring patient compliance.