Radicular cyst is the most common cyst in the mandible. It usually presents in the later age of life because the formation of the cyst is the last step in a progression of inflammatory events following a periapical inflammatory lesion. The cyst usually goes unnoticed because of the size that is rarely palpable, and it is often painless. In this paper, we present a 12 year-old girl who developed a relatively large cyst for the age. The outline of management is discussed.