Objective To explore the formation mechanism of peritumoral brain edema(PTBE)by vascular endothelial growth factor(VEGF).Methods 40 biopsies were obtained from 37 patients.Inmunohistochemical staining and Western blot were performed to detect the expression of VEGF protein.Reverse-transcriptase polymerase chain reaction(RT-PCR)was used to analyze the presence and quantity of VEGF mRNA.The extent of PTBE was estimated as an edema index(EI)based on preoperative magnetic resonance imaging.Results In VEGF-positive cases,a decreasing gradient of VEGF protein expression was observed with increasing distance from tumors(0.38±0.08,0.20±0.03,0.04±0.02).In meningiomas,the protein level and the mRNA level were congruent and the expression of both protein and mRNA had a significant correlation with EI(protein: r =0.892,RNA: r =0.875,P ＜ 0.05).However,in peritumoral areas,protein level were not consistent with the mRNA level.Protein results showed high correlation with EI(r =0.912,P ＜ 0.05),but mRNA almost was almost undetectable(0.06±0.02).Conclusion VEGF is impartant on PTBE.It is concluded that VEGF macromolecules are secreted by tumor tissue and enter peritumoral normal brain tissue to induce edemagenesis in meningiomas.