Urinary diversion by a vesico-sigmoidostomy was performed in fourteen dogs. The animals were randomly divided into two groups. Group 1 had an isoperistaltic intussusception of the sigma proximal to the vesico-sigmoidostomy. Group 2 was used as control without intussusception. In the postoperative course, serum creatinine, chloride, pH, bicarbonate, base-excess were controlled over a period of four months twice weekly. Additionally, IVPs were taken in all dogs and rectograms performed in the intussuscepted group. While IVPs and creatinine values demonstrated normal postoperative kidney function in all dogs of both groups, acidbase parameters including chloride were significantly (p less than 0.001, Wilcoxon test) better in group 1. Intussusception of the sigmoid colon is a reliable operative way to significantly reduce hyperchloremic acidosis in the course of urinary diversion into the sigmoid colon, while the fecal stream remains undisturbed.