We evaluated the long-term effects of percutaneous nephrolithotomy (PNL) on renal morphology and vascular resistance. Parenchyma thickness, echogenicity and resistive index (RI) of upper, middle and lower poles of operated and contralateral kidneys of 41 patients with 82 renal units who underwent unilateral PNL with single pole access between 2000 and 2002 were examined separately by color Doppler ultrasonography. Mean patient age and duration between PNL and evaluation time were 38.29 +/- 11.53 years and 46.44 +/- 10.9 months, respectively. In operated kidney, mean RI, parenchyma thickness and echogenicity of the access pole were not statistically different than those of the adjacent two poles (0.608 +/- 0.053 vs. 0.608 +/- 0.052 for RI, P=0.895; 11.46 +/- 2.58 vs. 11.41 +/- 2.68 mm for parenchyma thickness, P=0.838; 0.049 +/- 0.31 vs. 0.073 +/- 0.33 for parenchyma echogenicity, P=0.160, respectively). Although mean RI and parenchyma thickness of access pole were statistically significantly different than the mean values of contralateral kidney (0.562 +/- 0.032 and 14.31 +/- 1.37 mm, respectively), no statistical difference was found between mean parenchyma echogenicities of both of them (echogenicity of contralateral kidney was 0, P=0.317). No significant difference was found between the average echogenicities of the three poles of the operated and contralateral kidneys (0.063 +/- 0.32 vs. 0, P=0.080). In 14 patients RI decreased from 0.694 +/- 0.058 to 0.602 +/- 0.056 in operated kidney (P=0.001) and from 0.604 +/- 0.06 to 0.559 +/- 0.031 in contralateral kidney (P=0.018) following PNL. It seems that PNL does not cause renal scarring, renal parenchymal loss or increase in renal vascular resistance in the long term. However, prospective studies must be performed for more definitive conclusions.