Neurocutaneous melanosis (NCM) is a rare congenital neurocutaneous syndrome characterized by large or multiple congenital melanocytic nevi and benign or malignant melanocytic tumors of the leptomeninges. The authors report the case of a 5-month-old girl with congenital giant melanocytic nevi who presented with symptomatic hydrocephalus. A right frontal ventriculostomy was performed in the patient. Magnetic resonance imaging demonstrated melanocyte accumulation within the hippocampi, medulla, and cerebellum. Cerebrospinal fluid cytology revealed no presence of melanocytes. A ventriculoperitoneal shunt was placed; the patient's neurological condition improved and she was discharged home in good condition. The diagnosis of neurocutaneous melanosis should be considered in a case in which an infant or child presents with hydrocephalus and either large or multiple (> or = 3) congenital melanocytic nevi. Although our patient's neurological status improved following treatment for hydrocephalus, there is no definitive therapy for NCM and symptomatic patients have a poor prognosis. Our case illustrates to the neurosurgeon the importance of recognizing the likelihood of underlying pathological conditions of the central nervous system in a child with cutaneous melanocytic nevi.