The goal of this study was to evaluate the effect of unilateral ureteral ligation on blood constituents, renal histopathology and ultrasonography in dogs. A total number of 25 apparently healthy adult mongrel dogs found Assiut City, Egypt, were subjected to study. Animals were divided into five equal groups: the left ureter was ligated for 2, 7, 14 and 21 days in groups, I, II, III and IV, respectively, while group Vrepresented the control group. The animals in groups I, II, III and IV were euthanized on days 2, 7, 14 and 21, respectively. Right and left uretronephrectomies were performed and specimens were taken for the histopathological examination. Results revealed significant increases in total leucocytes and neutrophils counts from day 2 to day 17. There were significant decreases (p0.01) in total red blood cell (RBC) count and packed cell volume (PCV)% at day 14. Creatinine level was significantly increased on days 7 and 17. Histopathological changes were varied from glomerular swelling and congestion to glomerular atrophy. In conclusion, serum creatinine was highest on days 3 and 7, while creatinine clearance was lowest at day 7. The serum blood urea nitrogen (BUN) was the highest at day 21. Major histopathological changes were observed on day 21. These changes were compatible with the ultrasonographic and biochemical findings.