Supratentorial arachnoid cysts are usually asymptomatic and may be discovered by chance at autopsy; however, infratentorial arachnoid cysts, which correspond to liquid forms enclosed by an arachnoid sheet but whose pathogenesis is unknown, might cause symptoms. They don't need to be treated if they're asymptomatic and were discovered by chance. A variety of neurological symptoms can be present depending on their localization. Intracranial dermoid cysts are uncommon tumours that develop from ectopic epithelial cells in the brain. They are benign, slow-growing, and rarely rupture. The association between the two diseases is extremely rare and when it is present may suggest the existence of a common factor. We present a unique case of a young girl who developed headache and ataxia as a result of an intracranial infratentorial dermoid cyst and an arachnoid cyst of the cerebellopontine angle. Complete removal of the dermoid cyst and drainage of the cyst leads to a full recovery. Dermoid and arachnoid cyst are two pathologies with a possible common embryogenic factor, early surgery can give a better outcome in the long term.