The kidney is one of the organs that highly susceptible to age-related tissue damage. Several human and animal studies show decline in renal function with age. We examined the effect of endothelin-1 on age-related changes on renal function and whether this effect is mediated by ET-1 receptor types A or B. Also, we investigated the hemodynamic response to ET-1 and ET-1 receptor antagonist. Two age groups of male rats were used: young (4–5 months) and old (19–20 months). Each group was subdivided into four experiments in which hemodynamic and renal function data were measured after administration of saline (control group), acute intravenous injection of endothelin-1 (ET-1 group), administration of BQ-123, ETA receptor antagonist, 20 minutes before ET-1 (ETA antagonist group) and administration of BQ-788, ETB receptor antagonist, 20 minutes before ET-1(ETB antagonist group). We found that aging is associated with elevated mean arterial blood pressure and reduced renal function data. ET-1 injection resulted in more pressor response in old rats and more reduction of renal function data in young rats. Pretreatment with BQ-123 improved renal function with more augmentation in old rats while BQ-788 pretreatment has no effect on renal function. These results indicated that ET-1 and ET-1A receptor play a crucial role in age-related change in renal function.