The present studies were performed to determine the contribution of EP₂ receptors to renal hemodynamics by examining afferent arteriolar responses to PGE₂, butaprost, sulprostone, and endothelin-1 in EP₂ receptor-deficient male mice (EP₂−/−). Afferent arteriolar diameters averaged 17.8 ± 0.8 μm in wild-type (EP₂+/+) mice and 16.7 ± 0.7 μm in EP₂−/− mice at a renal perfusion pressure of 100 mmHg. Vessels from both groups of mice responded to norepinephrine (0.5 μM) with similar 17–19% decreases in diameter. Diameters of norepinephrine-preconstricted afferent arterioles increased by 7 ± 2 and 20 ± 6% in EP₂+/+ mice in response to 1 μM PGE₂ and 1 μM butaprost, respectively. In contrast, afferent arteriolar diameter of EP₂−/− mice decreased by 13 ± 3 and 16 ± 6% in response to PGE₂ and butaprost. The afferent arteriolar vasoconstriction to butaprost in EP₂−/− mice was eliminated by angiotensin-converting enzyme inhibition. Sulprostone, an EP₁ and EP₃receptor ligand, decreased afferent arteriolar diameter in both groups; however, the vasoconstriction in the EP₂−/− mice was greater than in the EP₂+/+ mice. Endothelin-1-mediated afferent arteriolar diameter responses were enhanced in EP₂−/− mice. Afferent arteriolar diameter decreased by 29 ± 7% in EP₂−/− and 12 ± 7% in EP₂+/+ mice after administration of 1 nM endothelin-1. These results demonstrate that the EP₂ receptor mediates a portion of the PGE₂ afferent arteriolar vasodilation and buffers the renal vasoconstrictor responses elicited by EP₁and EP₃ receptor activation as well as endothelin-1.