The radiographic and CT appearance of 20 cases of chondrosarcoma were correlated with histological grade and type of matrix. Features which were useful in predicting histological grade included (a) margins between bone and tumor (radiograph), (b) morphology of calcification (radiograph, CT), (c) distribution of calcification within the lesion (radiograph, CT), (d) pattern of tumor growth within soft tissues (CT), and (e) presence of necrosis (CT). Tumor/soft-tissue margins were usually well defined on the CT scan regardless of grade.