We report a rare case of primary nasal and paranasal sinus cysts. The patient was a 4 year-old female, whose chief complaint was right exophthalmus. Although CT and MRI were performed preoperatively, primary cyst was not diagnosed at that time. Taking malignant tumors into consideration, endoscopic endonasal sinus surgery was performed under general anesthesia. Intraoperatively, multiple cystic lesions containing mucous effusion were observed and were opened to be a mono-cavity. After 10 months' follow up no recurrence has been noted. To our knowledge, this is the first case report of primary and multiple paranasal sinus cysts in a child.