Ureterocele is a cystic dilatation of the terminal intravesical ureter; the therapeutic options are different and correlated on upper and lower urinary tract anatomy. The goals of treatment include control of infection, protection of ipsilateral and controlateral renal units and maintenance of vesicoureteral continence. The endoscopic approach is still debated; many authors report a higher risk of post-operative vesticoureteral reflux and further surgery. When the intravescical ureterocele is associated with the upper pole of a duplex system a small endoscopic transverse incision as definitive treatment has gained support in more than 90% of cases. We report a case of intravesical ureterocele with a complete duplex system, in a young woman treated by endoscopic incision as "smiling mouth" with good results of 6 months follow-up.