The effects of different prostaglandins (PG) on serial determinations of renal blood flow (RBF), mean arterial blood pressure (MABP), renal vascular resistance (RVR) and renin release were investigated in the conscious, chronically instrumented dog. 2 months after right-sided nephrectomy, female beagle dogs (n=6) were implanted with an electromagnetic flow probe and an inflatable pneumatic cuff around the left renal artery, and a catheter was inserted into the aorta above the renal artery. In repeated experiments, different prostaglandins (PGA_1, E₁, E₂ and F_2α) were infused above the renal artery at increasing doses (infusion time 15 min, doses 0.03–1.0µg min^-1 kg^-1). Lower and medium doses induced an increase of RBF, which returned to or were slightly below control levels with higher doses. PGA, appeared to be the most potent vasodilator with a significant hypotensive activity and the greatest augmentation of RBF. Simultaneously, renin release was most pronounced by PGA,.