To define the incidence of non-A, non-B (NANB) hepatitis and evaluate possible risk factors, we reviewed records of 163 patients on chronic dialysis during a 3-year period. 23 cases of NANB hepatitis occurred, 13 (27%) in 49 center dialysis, 8 (10%) in 77 home hemodialysis (p < 0.02) and 2 (5%) in 37 peritoneal dialysis patients (p < 0.01).Hepatitis patients received significantly more transfusions than controls. Numbers of transfusions and of patients transfused were not significantly different in center patients compared to home and peritoneal. 8 NANB patients received no transfusions. NANB was the most common cause of hepatitis in our unit (68%). Although transfusions were a likely etiologic factor, to explain the increased risk in center dialysis patients, disease in patients not transfused and development of NANB hepatitis without a known parenteral exposure in a physician assigned to the Nephrology Service, we feel another etiologic factor was important, the dialysis center.