This preliminary study examined reno-vascular injury sustained by the multipapillary porcine kidney in acute and chronic complete ureteric obstruction. In combination with measurement of upper tract pressure, regional function was assessed by [99mTc]-dimercaptosuccinic acid (DMSA) uptake and qualitative renal perfusion, by resin casting of the arterial tree prior to scanning electron microscopy (SEM). In acute obstruction, segmental defects were noted in the renal poles on both [99mTc]-DMSA scanning and casting. On SEM there was a polar afferent arteriolar vasodilatation after 30 min of obstruction and, subsequently, a segmental reduction in cortical perfusion. In kidneys that had been obstructed for 20 days, we observed a marked reduction in outer cortical perfusion coincident with afferent arteriolar vasoconstriction. The pathogenesis and significance of segmental injury to the multipapillary kidney in obstructive uropathy is discussed.