Arachnoid cysts (ACs) are congenital malformations that may develop anywhere in the subarachnoid space along the cerebrospinal axis but are mostly observed in the temporal fossa and Sylvian fissure, predominantly in the left side. ACs account for 1% of all intracranial space-occupying lesions. ACs are a potential risk factor for subdural haematoma in all age groups following a traumatic head injury. Although an intracystic haemorrhage of AC without evidence of a head trauma is very rare, it may particularly develop in children and young adults who spend much more time engaged in games and forced physical exercise. Here we present a rare case of spontaneous intracystic haemorrhage of AC with a subacute subdural haematoma and provide a review of the literature.