Currently, laparoscopic-assisted colon pull-through (LACPT) is the treatment of choice for male patients with high-type imperforate anus and rectourethral fistula. Since laparoscopy was introduced for treating this condition, reports concerning post-LACPT complications are rare. Here we discuss the case of a boy, now 3.5 years old, born at 37 weeks' gestation weighing 2,300 g, who was diagnosed with rectobulbar urethral fistula (RUF) at birth. LACPT was performed when the boy was 11 months old and weighed 7.2 kg. No intraoperative complications occurred, and the initial post-LACPT course was uneventful. When he was 2 years old, he developed dysuria requiring urethral catheterization. Diagnostic radiology confirmed a large cystic mass behind the bladder, suggestive of a posterior urethral diverticulum (PUD). Histopathology of the excised mucosa of the cyst showed colonic mucosa, confirming that the cyst was indeed an enlarged residual RUF. We discuss our treatment and our approach to prevention.