Purpose: The present study was planned to investigate morphological, functional and histological properties of the natural ureterocloacal for in birds as well as to provide an appropriate information which may contribute to rectosigmoidal pouch surgery and to decrease its complications. Materials and Methods: Thirty chickens (Gallus domesticus, 26 broilers, 4 layers) with a mean weight of 1870 +/- 88 g were used for this study. Histological and morphological evaluation of the cloaca was performed. Urethral reflux was estimated using X-rays. Results: We found that the cloaca had three parts from cranial to caudal: coprodeum, urodeum and proctodeum respectively. A coprourodeal fold (CUF) between the coprodeum and urodeum and a uroproctodeal fold between the urodeum and proctodeum were detected. Settling of the muscle clusters both in the ureter and urodeum near the opening area appeared to be a strong sphincter structure and the ureters are opened to a structure covered by a transitional epithelium, which is similar to bladder in humans (connecting two identical epithelia). According to X-rays following the administration of a radio-opaque substance, there was no ureteral reflux in any of them. Conclusions: The natural urointestinal structure in birds has a spontaneous ureterointestinal anti-reflux opening. The coprourodeal fold that prevents the mixing of faeces and urine, inhibits the effects of increased pressure and prevents the reflux of urine to the upper segments is provided with many of desired hinders properties for urointestinal diversion.