The preoperative diagnosis of cavernous sinus invasion remains difficult and controversial, and there are currentlyno reliable histological or molecular markers that predict pituitary tumour behaviour and response to treatment.We evaluated 45 patients with pituitary adenoma. The results have shown that the sensitivity of MRI for indicatingcavernous sinus invasion in this prospective study was 60%, specificity 85%, positive predictive value 83.33%,negative predictive value 62.96%. Forty-five specimens of pituitary adenomas were analyzed for expression of F8,VEGF, Ki-67, c-myc, bcl-2, nm23 and MMP-9 immunoreactivity using immunoperoxidase staining. MVD wasassessed using F8-related antigen. The results have shown that MVD of invasive pituitary adenomas was significantlyhigher than that of noninvasive (P<0.001). There was an association between the invasion of pituitaryadenomas and Ki-67 LI (P=0.039) or the expression of VEGF (P<0.001) and MMP-9 (P<0.001). But c-mycLI and bcl-2 expression have no association with invasiveness of pituitary adenomas (P=0.061 vs. P=0.201). Onthe other hand, there is an inverse relationship between nm23 expression and tumor invasion (P<0.001). Inconclusion, parasellar extension of pituitary adenomas through the medial wall of the cavernous sinus diagnosed atsurgery, can be determined by radiology with sensitive gadolinium-enhanced MRI. Although our study has shownthat MVD and the expression of VEGF, Ki-67, nm23 and MMP-9 have associations with invasiveness of pituitaryadenomas, they are lack of specificity. These markers can only provide some useful informations on the therapeuticstrategy of pituitary adenomas.