A girl, ultimately diagnosed as having profound ornithine transcarbamylase (OTC) deficiency, presented as a neonate with feeding intolerance, irritability, and seizures without concurrent hyperammonemia. Developing normally until ten months of age, the girl subsequently experienced two episodes of hyperammonemia, which were associated with focal seizures and residual hemiparesis. She continued to have profound neurologic impairment and seizures and died at 26 months of age, despite appropriate dietary protein restriction, sodium benzoate, and arginine supplementation. Symptomatic OTC deficiency has not been previously reported unassociated with hyperammonemia. The recurrent cerebrovascular episodes are distinctly uncommon in patients with urea cycle enzymopathies.