Carbon monoxide remains a significant cause of poisoning in children. Cerebral edema is often the cause of significant morbidity and mortality in exposed children. While lesions of the basal ganglia have been well documented, the advent of neuroimaging has allowed antemortem demonstration of infarctions of the globus pallidus and putamen with carbon monoxide intoxication. Acute hydrocephalus following carbon monoxide poisoning has been a rare occurrence. We report a 2 year 6 month-old boy who, to our knowledge, represents the first reported case in which repeat computed tomography documented the evolution of hydrocephalus due to carbon monoxide exposure in a child.