Laser enucleation and morcellation of the prostate is an increasingly used surgical management of benign prostatic hyperplasia. However, it can cause several complications including capsular perforation, ureteral orifice injury, and bladder mucosal morcellation injury. Herein, we report a case of severe postoperative dyspnea caused by neglected massive intraperitoneal fluid collection during laser surgery of the prostate. The patient experienced massive abdominal distension and severe respiratory difficulty after the procedure. Although immediate postoperative cystogram showed no leakage of contrast dye, the computed tomography scan of the abdomen and pelvis showed massive fluid collection in the abdominal pelvic cavity suggesting bladder wall injury. After percutaneous drainage of intraperitoneal fluid, abdominal distention and dyspnea were relieved.