Proliferative, apoptotic and angiogenic potentials in jaws and long bones osteosarcomas: a comparative immunohistochemical study. Osteosarcomas (OS) of the jaws are uncommon lesions that represent less than 10% of all skeletal OS. It has a behavioral pattern which is less aggressive than their long bones counterparts. This study performed an immunohistochemical comparison between jaws and long bones OS.The study involved 15 jaws and 15 long bones OS tissue samples for the period from 1986 to 2005. Age, sex, histologic subtypes and grades were recognized. The samples were immunohistochemically stained with monoclonal antibodies to Ki-67, P53 and vascular endothelial growth factor (VEGF).The mean age of the patients with jaw OS was a decade higher than that of long bones OS. A slight male predominance in jaw OS was found (1.14:1), which was more pronounced in long bones OS (2:1). The chondroblastic subtype was the predominant in jaws (66.66%), whereas (60%) of long bones OS were of osteoblastic subtype. The Ki-67 labeling index and the VEGF expression were significantly higher in long bones as compared with jaws OS, whereas there was no significant difference regarding the P53 expression between jaws and long bones OS.Jaws and long bones OS bear a comparable cell cycle dysregulation when quantified with P53 immunostaining, whereas the long bones OS have a higher proliferative and angiogenic capacity than their jaw counterparts when evaluated with Ki-67 and VEGF immunoexpressions respectively.© 2010 The Authors. Journal of Oral Pathology & Medicine © 2010 John Wiley & Sons A/S.