Neurocutaneous melanosis is a rare, congenital, non-inherited syndrome characterized by numerous and/or large congenital nevi with intracranial leptomeningeal melanocytosis. This report describes two patients, presenting with a giant congenital nevus involving a major portion of the posterior trunk with satellite congenital nevi scattered all over the body, who developed seizures at 4 and 6months of age, respectively. Changes in follow-up magnetic resonance (MR) examinations over an 8-year period were seen in case 1, while parenchymal melanocytic accumulation was reported in the region of the amygdala in case 2. These cases emphasize that neurocutaneous melanosis should be suspected in patients with giant congenital nevus with or without neurological symptoms. Also, neuroaxial MR screening should be performed in all cases and, ideally, before myelination of the brain to provide the highest sensitivity for detecting melanin deposits in the leptomeninges.