Necrotizing enterocolitis(NEC) is the most common life-threatening surgical emergency in neonates, and remains a major cause of morbidity and mortality. In addition to conventional laparotomy, intraperitoneal drains have been used for the treatment of perforated NEC, especially in extremely low birth weight(ELBW) infants. We report a case of perforated NEC with bacterial peritonitis in an ELBW infant managed with primary peritoneal drainage(PD) without further need for surgery. To our knowledge, this is the first documented Korean case of an ELBW infant where PD was used as primary treatment for perforated NEC. Primary PD is effective and safe in ELBW infants with perforated NEC; although it is not considered a definitive procedure, it should be considered in all cases where infants are too unstable to tolerate anesthesia and surgery.