A fifty-nine year-old male was hospitalized for exacerbation of chronic pancreatitis. As a gigantic cyst of the pancreatic tail was identified, it was fused with the jejunal loop. Due to persistent fever and severe symptoms in the storage and voiding phases, the patient was referred to a urologist. Because transrectal ultrasound examination revealed a fluid collection resembling the left seminal vesicle filled with purulent material, a transrectal puncture procedure was performed. The analysis of computed tomography scans led to the diagnosis of duplicated collecting system of the left kidney with the enormous ureter of the upper moiety that entered the prostate gland. In order to permanently decompress the hydronephrosed upper moiety of the left kidney, the patient was deemed eligible for endoscopic treatment. A transurethral incision through the bladder wall and the adjacent segment of the ectopic ureter was made with holmium laser under transrectal ultrasonography guidance, thus creating a neo-orifice of this ureter.