Tarlov cysts or perineural cyst are lesions of the nerve roots located at the sacral level and uncertain aetiology. Most of these cysts remain asymptomatic with no clinical relevance. The symptomatic cysts are uncommon and the usual symptoms are pain or radiculopathy. We report the case of a 53-year-old woman witha symptomatic cyst (with a history of frequency and urgency syndrom), that disappears after surgery.