OBJECTIVE Subjective improvement of patients who have undergone surgery for intracranial arachnoid cysts has justified surgical treatment. The current study aimed to evaluate the outcome of surgical treatment for arachnoid cysts using standardized interviews and assessments of neuropsychological function and balance. The relationship between arachnoid cyst location, postoperative improvement, and arachnoid cyst volume was also examined. METHODS The authors performed a prospective, population-based study. One hundred nine patients underwent neurological, neuropsychological, and physiotherapeutic examinations. The arachnoid cysts were considered symptomatic in 75 patients, 53 of whom agreed to undergo surgery. In 32 patients, results of the differential diagnosis revealed that the symptoms were due to a different underlying condition and were unrelated to an arachnoid cyst. Neuropsychological testing included target reaction time, Grooved Pegboard, Rey Auditory Verbal Learning, Rey Osterrieth complex figure, and Stroop tests. Balance tests included the extended Falls Efficacy Scale, Romberg, and sharpened Romberg with open and closed eyes. The tests were repeated 5 months postoperatively. Cyst volume was pre- and postoperatively measured using OsiriX software. RESULTS Patients who underwent surgery did not have results on balance and neuropsychological tests that were different from patients who declined or had symptoms unrelated to the arachnoid cyst. Patients with a temporal arachnoid cyst performed within the normal range on the neuropsychological tests. Seventy-seven percent of the patients who underwent surgery reported improvement, yet there were no differences in test results before and after surgery. Arachnoid cysts in the temporal region and posterior fossa did not influence the preoperative results of neuropsychological and motor tests. The arachnoid cyst volume decreased postoperatively (p < 0.0001), but there was no relationship between volume reduction and clinical improvement. CONCLUSIONS The results of this study speak against objectively verifiable improvement following surgical treatment in adults with intracranial arachnoid cysts.