Objective- To evaluate the some serum biochemical alterations after urinary diversion with colonic segment.Design- Experimental in vivo study.Animals- five adult healthy mixed breed dogs of both sexes weighing between 25-40 kg. Procedures- In this approach, fifteen centimeters of the descending colon with preservation of its mesenteric vessels was resected and this segment longitudinally was opened and flushed with copious amount diluted Povidin Iodine 0.1% and the remaining colon re-anastomosed with seromuscular sutures. Then two ends of transected ureters were drawn into the resected colon by mosquito hemostatic forceps and simple interrupted sutures were placed between the ureters and the colonic mucosa for uretero-colonic anastomosis. The uretero – colonic part in a cap form transplanted to partially cystectomized bladder with one layer of cushing pattern suture. In this study, blood urea nitrogen (BUN), serum creatinine, Ca, P, Na, K, Cl ions, pH, and bicarbonate levels were measured before surgery and at the 1, 2, 3, 4, 5, 6, 7, 10, 15, 20, 25, 35 and 45 postoperative days.Results- BUN and serum creatinine concentrations were increased significantly at first three postoperative days but regressed to the normal levels gradually. After operation, hyperchloremic metabolic acidosis with low sodium and potassium levels was diagnosed in 5 dogs. In all animals, hypocalcemia and hyperphosphatemia were significant. All of the biochemical parameters except calcium, phosphor, and sodium regressed to the normal levels within the study.Conclusions and Clinical Relevance- In conclusion, the salt-loss syndrome and metabolic acidosis are the most complications after urinary diversion with colonic segment in dog.