Abstract: Objective: To reveal the pathologic significancy of strongly polarible crystals in kidney allografts.Methods:90 surgically removed kidney allografts were morphometrically observed under polarized light microscope with a fixed microrula. Results:The crystals were detected in 52 renal allografts with the positive rate of 57.8%. The average number was of 12 per 10 high power fields （HPF） with the size of 8-80μm in great diameter. 22 of 23 allografts of acute rejection and 21 of 27 allografts of chronic rejection showed the crystals （95.7% and 77.8%, respectively）. But there were no crystals detected in 2 allografts of hyperacute rejection and in donor boipsies. Only 9 of 36 grafts failed of other complications such as infection, acute tubular necrosis were positive for crystals. The strongly polarible crystals were located in tubular lumens and within the cytoplasm of tubular epithelia, usually accompanied bytubular atrophy, necrosis and tubulitis.Conclusion:The deposition of polarible crystals are morphologic evidence of the failure of transplanted kidneys and may be associated with the functional insufficiency of tubular epithelia.