Arachnoid cysts are cavities filled with liquor, usually localized on the floor of the middle cranial fossa. Clinically, they are usually asymptomaticand can sometimes be presented with increased intracranial pressure syndrome and epileptic seizures. We present a patient who, after a slight head injury in a accident develops an increased intracranial pressure syndrome followed by an epileptic seizure. Based on the clinical course and diagnostic processing, we want to draw attention doctors who are in a position to inspect these patients that apparently slight head injuries can be complicated and dangerous for the lives of the premorbid intracranial condition of the injured.