Internal herniation through congenital sigmoid mesocolic defect as a cause of neonatal intestinal obstruction is rarely reported. Clinical judgement combined with judicious use of investigations and prompt exploration is essential to provide immediate relief of the obstruction and salvage the herniated loop of bowel, which otherwise might lead to morbidity and even death. We present a neonate with internal herniation of the ileum through a congenital mesocolic defect which was diagnosed by a prompt abdominal exploration in view of persistent clinical signs of intestinal obstruction. The relevant literature is also discussed highlighting the rarity of neonatal presentation of sigmoid mesocolic defect.