We report a rare case of erosion of an inflatable penile prosthesis reservoir into the bladder that was managed with a different approach from the literature by preserving the existing reservoir. Inflatable penile implant was applied to a 54-year-old male patient who had undergone with a robot-assisted radical prostatectomy operation due to localized prostate cancer 2 years before. Two months after the operation, the patient referred to our clinic with predominant symptoms of lower urinary tract system associated with scrotal pain and swelling. The urinary system ultrasonography (USG) and the lower abdomen magnetic resonance imaging (MRI) demonstrated that the reservoir of the penile prosthesis was in the bladder. Cystoscopy confirmed that the reservoir was in the bladder. According to literature the reservoir was surgically removed from bladder. After bladder repair, the rectus muscles were repaired creating a space between the rectus muscle and the skin, where the reservoir was placed. After postoperative observation, the patient was discharged without any infection and regression of the lower urinary tract symptoms. No problem was referred by using the penile prosthesis when at 1-month and 3-month follow up and the patient was not uncomfortable in this regard. In conclusion no drawback occurred by using the old reservoir.