Tumor and tumor-like lesion of the patella are extremely rare. The following have been reported: giant cell tumor; osteoblastoma; osteoid osteoma; chondroblastoma; solitary osteochon droma; chondroma; ganglion; simple bone cyst; aneurysmal bone cyst; hyperparathyrodism (brown tumor); malignant lymphoma; haemangioendothelioma; haemangima; primary osteosarcoma; plasmocytoma and metastases. Chodroblastoma in patella were very rare and first repoted by Jerone Cohren in 1963. On review of our literatures, we could not find reported case in Korea. The purpose of this paper is to present an unusual case of chondroblastoma of the patella.