Osteochondroma is a development anomaly, rare in clavicle, once it suddenly increase in size or pain, malignant chondrosarcomatous degeneration have to be considered. Herein we report a case of 45 years old married female, she suffered from pain and increasing size of an anterior chest wall mass, which has been noted for more than ten year. She denied any symptoms of respiratory or circulation or neurological disturbance of upper limb. The chest roengenogram and CT scan revealed a bony mass over the medial end of right clavicle, the mass protruded ratherly inward but didn’s compress the superior vena cava. Aurgical treatment was carried out and pathological examination reported that it was typical histology feature of osteochondroma.