There are substantial evidence suggesting that DNA content of tumors may provide the prognostic information with independent significances. With the advent of computer and video technology, image analysis becomes a practical method of measuring DNA that also makes it possible to classify cells. Among the patients who were operated and diagnosed as bone tumor at Department of Orthopedic Surgery, Korea University Hospital, from March 1992 to March 1995, we evaluated 19 cases by image cytometry and studied them. Among 19 case, 4 cases were fibrous dysplasia, 2 cases chondroma, 3 cases osteosarcoma, 2 cases chondrosarcoma, and 8 cases were metastatic bone tumors. Total benign tumors were 6 cases and malignant tumors were 13 cases. All benign tumors were diploid and all malignant tumors but one metastatic tumor were aneuploid. As a result, DNA quantitation by image analysis is effective in the differential diagnosis of malignancy in bone tumor. It seems that DNA quantitation will be used on the evaluation of tumor staging and prognosis by further clinical study.