Mollaret's meningitis is a recurrent aseptic meningitis with characteristic clinical features and Mollaret cells in cerebrospinal fluid (CSF). We report here on a case of Mollaret's meningitis in a 3-year-old boy who presented with three episodes of aseptic meningitis within a 4-month period. Each episode was characterized by sudden onset of meningeal irritation followed by spontaneous remission in several days. He was free of neurological symptoms between the episodes. In the acute phase of each episode, his CSF revealed polymorphonuclear pleocytosis with normal protein and glucose concentrations. In addition, some epithelial cell clusters in the CSF were evident during the third episode. No pathogenic microorganisms were identified in CSF or blood cultures. Brain MRI revealed a benign pineal cyst, 0.8 cm in diameter, and we suspected that the epithelial cell clusters represented the ruptured cystic wall and that the recurrent aseptic meningitis was triggered by spontaneous rupture of the cyst.