Meniscus cysts are mostly seen with meniscus tears, and arthroscopic decompression of cysts is gaining great importance in their treatment. In this study, we present a medial meniscus anterior horn cyst without an accompanying tear in the meniscus. A 33-year-old male patient was seen with pain and a palpable mass in his right knee. He complained that the severity of the pain had increased over the previous year. After the clinical and radiologic examinations, a painless, fixed soft tissue mass averaging 4 X 5 cm was located just medial to tuberositas tibia. The cyst was decompressed arthroscopically. In the 18th month of follow up, the mass had totally disappeared and the patient had no pain. Medial meniscus cysts are seen nine times fewer than lateral meniscus cysts. They are mostly accompanied with meniscal tears. Total meniscectomy with arthrotomy, isolated cyst excision, cyst excision, and partial meniscectomy with arthrotomy,and arthroscopic partial meniscectomy with cyst decompression are treatment modalities. Arthroscopic meniscal cyst decompression is an important treatment choice and should always be taken into consideration with low morbidity, short recovery period, low recurrence rate, preservation of range of motion, and permission for early mobilization and rehabilitation of the joint.