Abdominal compartment syndrome (ACS) involves adverse physiologic consequences arising from the increased intra-abdominal pressure, leading to high mortality. However, this syndrome has been scarcely reported in pediatric emergency settings. We describe a 10-year-old boy with ACS presenting with painful abdominal distension, oliguria, and dyspnea. Despite the absence of known congenital anomalies, he had undergone frequent episodes of constipation since 5 years of age, and had not defecated for recent 2 months. With computed tomography scans showing the entire colorectal distension, his manifestations were considered to have stemmed from congenital aganglionic megacolon, which had gone undetected. This case underlines the needs for considering ACS and consequent surgical decompression in a child with severe abdominal distension.