Background: Meningiomas are considered extra-axial and benign tumors. Though they are pathologically classified as benign, non-benign and other types, it seems that information derived from this classification cannot explain the behavior of the tumor. Pretumoral brain edema (PTBE) is one of the signs that has been less thoroughly studied, and still there is not a single consensus about its mechanism. Despite the benign and extra-axial manifestations of meningioma, in more than 60% of cases, these tumors have PTBE. The goals of this study were to show the role of the level of progesterone positivist in tumor cells as a behavioral factor and to find different features in the MRI and CT scans of meningioma patients that might be related to this issue and also to PTBE.Materials and methods: In this study, 77 patients with intracranial meningiomas who referred to the Neurosurgery Department of Imam Khomeini Hospital in Tehran were followed prospectively between 1999-2003. Initial CT scans and MRIs (T1, T2) were performed on each patient, and certain imaging features of the tumors— including the diameter, volume, location, contour, presence or absence of PTBE, and the shape of tumor—were detected. Then a comprehensive comparison of these factors with surgical and pathological findings, clinical presentations, and immunohistochemical (IHC) staining for estrogen receptors (ER) and progesterone receptors (PR) were carried out. Results: Tumors with higher PR levels had smaller sizes, and their contours were smoother. Images showed that these tumors were less invasive, in that in more than 50% of the cases, the arachnoid space (AS) around the tumor could be observed, and it was less probable to see PTBE. Instead, the duration of the disease was longer, and the intrasurgical bleeding was less.Conclusions: The results of this study show that the future behavior of intracranial meningioma tumors cannot be predicted based on such features as diameter, location, contour, and volume. Instead, we must obtain more in formation about the tumors’ cells in order to predict the future behavior of these tumors.