This study was performed to investigate the proper method for evaluating renal function in miniature pigs with unilateral ureteral obstruction. Experimental unilateral renal damage was induced after ligation of unilateral right ureter in 3 miniature pigs. On the 3rd post-operative day, scintigraphic images were obtained after 12 mCi of 99mTc-diethylentriamene pertaacetate (DTPA) intravenous injection. Renography showed that radiopharmaceutical uptakes in the right kidney were lower than those of left kidney uptakes as early as at 3 days after surgical operation. The static images of 99mTc-DTPA enabled us to measure the relative renal function in miniature pigs with unilateral ureteral obstruction. In conclusion, renography using 99mTc-DTPA was the useful diagnostic method to evaluate the renal function in miniature pigs.