Osteoid osteoma is a distinctive benign lesion characterized by a less then 2 cm, pea-like mass of abnormal bone (nidus). The common sites of osteoid osteoma are femur, tibia, humerus, spine and talus. Mastoid tip, clavicle, acetabulum, coccyx, rib, hamate, scapula and scaphoid are rare sites of osteoid osteoma. Osteoid osteoma of the patella is also very rare and on review of literatures we could find only one reported case which was treated by surgical excision. We also experienced one case of osteoid osteoma located at the patella, so we report this case with review of literatures.