End-stage renal disease is a devastating complication of essential hypertension and type II diabetes mellitus, conditions that commonly occur together. We and others have previously suggested that the outcome of both conditions may be influenced by more aggressive treatment. We examined a large general medicine outpatient population; 72% were black and 41% were diabetic (95% type II). Decreased renal function, defined as a serum creatinine ≥mg/dL, developed in 18.1%. A multivariable logistic regression analysis identified glucose control, systolic blood pressure level, and male gender as indicators of decreased renal function. These data suggested that both glucose and blood pressure control may decrease the frequency of impaired renal function. However, when these variables were controlled, blacks still had almost twice the risk for renal dysfunction of whites. The data draw attention to, and elucidate the exceptionally high incidence of renal dysfunction in hypertensive blacks with or without diabetes. Further, they may explain the inordinate numbers of blacks with hypertension requiring dialysis. Prospective trials to test the efficacy of blood pressure and glucose control on the course of renal disease in hypertensive and/or type II diabetic patients are warranted. Am J Hypertens 1990;3:69-75