To investigate the clinical characteristics of chondroblastoma with an emphasis on lesions located in the long bone diaphysis,we reviewed the clinical data of 7 patients with histologically proven chondroblastoma treated in Tianjin Medical University Cancer Hospital and Fudan University Cancer Hospital between January 1995 and May 2009.There were two rare cases of chondroblastoma in the long bone diaphysis.One patient with a lesion in the tibial diaphysis underwent intralesional curettage and bone grafting,and the postoperative bone function was measured as excellent according to the Enneking scoring system.The patient was still alive upon follow-up at 60 months.The other patient with a lesion in the humeral diaphysis underwent resection,and the postoperative bone function was excellent at 48 months,at which there was no evidence of recurrence or metastasis.Thus,except for the distinctive site of the long bone diaphysis,which made diagnosis difficult,the patients’ ages,symptoms,X-ray and CT images,treatment,and prognosis were in accordance with typical lesions in the epiphysis and metaphysis.The diagnosis of chondroblastoma in the long bone diaphysis significantly depends on histopathologic characteristics. To investigate the clinical characteristics of chondroblastoma with an emphasis on lesions located in the long bone diaphysis, we reviewed the clinical data of 7 patients with histologically proven chondroblastoma treated in Tianjin Medical University Cancer Hospital and Fudan University Cancer Hospital between January 1995 and May 2009. There were two rare cases of chondroblastoma in the long bone diaphysis. One patient with a lesion in the tibial diaphysis underwent intralesional curettage and bone grafting, and the postoperative bone function was measured as excellent according to the Enneking scoring system. The patient was still alive upon follow-up at 60 months.The other patient with a lesion in the humeral diaphysis underwent resection, and the postoperative bone function was excellent at 48 months, at there was no evidence of recurrence or metastasis.Thus, except for the distinctive site of the long bone diaphysis, which made diagnosis difficult, the patients’ ages, symptoms, X-ray a nd CT images, treatment, and prognosis were in accordance with typical lesions in the epiphysis and metaphysis. The diagnosis of chondroblastoma in the long bone diaphysis significantly depends on histopathologic characteristics.