Citrullinemia is an autosomal recessive urea cycle disorder that causes ammonia and other toxic substances to accumulate in the blood. It manifests with lethargy, brain edema, seizures, coma and possibly death. Electrocardiographic (ECG) abnormalities in patients with type 1 citrullinemia have not been reported so far. A long QT interval may be congenital or may be acquired such as in the use of antiarrhythmic drugs or during electrolyte imbalances. The neonate reported in this article had a long QT interval and hyperammonemia.