Our aim in this study was to evaluate the use of diffusion-weighted imaging (DWI) for acute renal parenchymal changes occurring as a result of unilateral ureteral obstruction due to stones. Twenty four patients with obstructed and opposite unobstructed kidney were enrolled in this prospective study. DWI was used at two different b values (b = 0 s/mm(2) and b = 1000 s/mm(2)). Apparent diffusion coefficient (ADC) measurements were completed on the upper pole, central section and lower pole parenchyma of both kidneys. ADC values were calculated. The unpaired t test was used to assess differences between the groups. The results of measurements identified a reduction in ADC values in obstructed renal parenchyma compared to unobstructed opposite renal parenchyma. The reduction in ADC values was greater in the upper and lower pole parenchyma and was statistically significant (p < 0.001, for both). Diffusion changes in renal parenchyma due to acute unilateral ureteral obstruction linked to stone may be quantitatively shown with DWI. The reduction in ADC values was more pronounced in the upper and lower pole parenchyma.