Intracranial arachnoid cysts are cystic malformations found in both adults and children. While many are asymptomatic, some cause symptoms and warrant surgical treatment. In this prospective population-based study, we aimed to study the short- and long-term outcome after surgical intervention in children with arachnoid cysts referred to our centre. Twenty-seven pediatric patients (13 f. 14 m, mean age 9.4years) with de novo cysts were consecutively included during a 5-year period. The presenting symptoms were headache (n=12), balance disturbance and dizziness (n=6), seizures (n=6), hydrocephalus (n=5), and macrocephaly (n=1). Twenty-two patients underwent surgical treatment with either microsurgical (n=17) or endoscopic fenestration (n=5) of the cyst wall. Cyst volume was measured with OsiriX® software pre- and postoperatively. Short-term and long-term follow-up of all patients was conducted 3months and 8.6years (7-10.5years) postoperatively. Three months after surgery, 59% of the patients were improved regarding at least one major complaint, and average cyst volume was reduced to 33.3ml (0-145ml). At the long-term follow-up of 8.6years, 77% of the patients were improved regarding at least one symptom but subjective symptoms remained in 59%. There was no permanent postoperative morbidity. We found no association between radiological reduction of cyst volume and clinical improvement. Our findings support a restrictive attitude to surgery for intracranial arachnoid cysts, in the absence of objectively verified symptoms and signs or obstruction of CSF pathways.