Objective: the goal of this study was to evaluate the clinical, radiological,pathological factors relation to development of peritumoral edema in supratentorialmeningiomas, and to determine the exact implication of peritumoral edema inintraoperative and short postoperative prognosis.Patients and methods: fifty patients with supratentorial meningiomas weresubjected to clinical, radiological, and intraoperative assessment. postoperatively,clinical, pathological , and radiological assessment was done during a period of 3months. Factors possibly related to peritumoral edema, such as age, sex, seizures,deficit, tumor size, location, type of contrast enhancement, tumor margin,radiological plane of cleavage, intraoperative surgical plane of cleavage, brain tumorinterface, grade of removal , pial crossing vessels, and histopathology wereevaluated. Postoperatively, morbidity, radiological tumor residual, and edemaresolution also were evaluated. We defined the edema/tumor volume ratio as theEdema Index EI, and use this EI besides with edema volume in evaluation ofperitumoral edema.Results: factors that were associated with incidence of peritumoral edema wereradiological plane of cleavage(P<0.05), intraoperative brain tumor interface(P<0.05),surgical plane of cleavage(P<0.05), and crossing pial blood vessel(P<0.001), tumormargin integrity(P<0.1) was probably related. Factors that were associated withmore peritumoral edema were tumor size(P<0.05), radiological plane ofcleavage(P<0.05), tumor margin(P<0.05) , intraoperative brain tumorinterface(P<0.05), and surgical plane of cleavage(P<0.05), deficit presentation (P<0.1)was probably related. Postoperatively larger peritumoral edema influenced theoutcome. Tumors with peritumoral edema tended to be associated with morbidity(P<0.05), residual tumor(P<0.05) and secondary brain affection(P<0.05) onpostoperative imaging. A relationship between intraoperative and postoperativefactors was present and was statistically significant.Conclusion: in our results, deficit presentation, tumor size, radiological plane ofcleavage, tumor margin integrity, intraoperative surgical plane of cleavage, braintumor interface, and crossing pial vessels to the tumor were related to peritumoraledema. Also, larger peritumoral edema influence the outcome and was associatedwith postoperative morbidity, residual tumor and secondary brain affection onpostoperative imaging.