In patients with diabetic renal failure plasma advanced glycosylation end-products (AGE) levels are reported to be elevated and dialyzer of continuous ambulatory peritoneal dialysis (CAPD) is usually used with a high glucose concentration. Here, an immunohistochemical study on human AGE accumulation in vascular beds and peritonea of patients with chronic renal failure (CRF) or those on CAPD was undertaken. Further, the influence of aging was studied using AGE-specific monoclonal antibody. 1. AGE accumulation was observed in radial arterial walls (from vascular intima to smooth muscle layer) of diabetic patients with CRF. Even in some non-diabetic patients with CRF (n = 3/6), especially in those with a long history of CRF and dialysis treatment, similar positive staining was seen in vascular walls. No AGE staining was observed in any renal tissue of age-matched control subjects including tissue from patients with acute renal failure. 2. Although AGE accumulation was not seen in the peritonea of CRF patients with no prior CAPD therapy, it was seen in the mesothelial layers and in adjacent coarse connective tissues of peritonea from patients on CAPD (n = 6), even from as early as only 3 months of CAPD therapy. 3. AGE accumulation was observed in the vascular bed of the non-diabetic aged kidney with normal function, but not in that of the young kidney. Thus, AGE accumulation in the vascular bed may depend on the degree and term of renal impairment and on aging in addition to diabetes. AGE accumulation in the peritonea became positive following CAPD treatment, indicating that it might affect the efficiency of CAPD.