This is a report of a rare case of post-traumatic leptomeningeal cyst in a 25 year old female, who received depressed and compound fracture in the left fronto-temporal bone and linear fractures in the left temporal bone following a traffic accident. Plain skull series obtained one 4 months after the trauma demonstrates a leptomeningeal cyst measuring 2.0$ imes$1.5$ imes$0.5$ imes$cm in its dimension in the left fronto-temporal bone associated with linear fractures. Etiology, pathogenesis, symptoms and signs, roentgenological findings, differential diagnosis, prognosis and treatment of leptomeningeal cyst are discussed with a review of the literature.