Argininosuccinic aciduria is an autosomal recessive disorder characterized by hyperammonemia due to defects in the Argininosuccinate Lyase (ASL) gene. The presenting features in the neonatal-onset form of this disorder include, lethargy, poor appetite, irritability, vomiting, and poor control on breathing rate. Early diagnosis is extremely important for proper management of this condition. If left untreated, the patient may develop severe symptoms, such as hepatomegaly, developmental delay, intellectual disability, and in some cases could even lead to coma and death. The late-onset form of argininosuccinic aciduria is milder and symptoms, usually episodic, appear as a result of infection or stress.