Background: Bilateral or multiple Sylvian fissures arachnoid cyst (AC) are unusual and restricted to few case reports in the medical literature. There are some reports of association between familial Glutaric Aciduria type I and bilateral Sylvian fissure AC in some symptomatic children.
Case Report: Our case is an idiopathic example of bilateral sylvian fissure AC who became symptomatic at his sixth decade of life, and had no familial history.
Conclusions: This case is outstanding from several aspects: First, This is a rare occurrence of bilateral AC that became symptomatic in 6^th decade of life; second, this case is idiopathic (bilateral AC is usually secondary to hereditary metabolic diseases) ; Third, this case is a non familial
example of the disease.

Keywords: Arachnoid Cysts