In order to investigate the significance of prostacyclin and throm-boxere A2 in the pathegertsis of ischemic renal injury,the level of 6-keto-PGF1? and TXB2 in the plasma and the dissected slices of the kidneys of the rabbits with iscbemic renal injury was determined with RIA,It was found that 6-keto-PGF1? increased significantly in the outer and inner medullae,TXB2 increased significantly in all the renal slices,and the 6-keto-PGF1?/TXB2 ratio decreased significantly in the outer cortex 3 hours after reperfusion,The findings suggest that the imbalance between the synthesis of prostacyclin and thromboxane A2 might be resporsible for the decline and redistribution of renal blood flow in the early stage of acute ischemic renal failure.