Introduction:Brain edema associated with brain tumour is one of the most important factor contributing to the morbidity and mortality associated with brain tumour. The major mechanism for edema formation within and around brain tumour is abnormal permeability of newly created microvessels in the growing tumour. It was found that endothelial proliferation is common in malignant gliomas and that new tumour vessels are derived from previously existing vessels. However, these newly formed vessels are often defective. These defective vessels form an ineffective barrier and allow leakage of plasma exudates into the surrounding brain 1 . It is thought that enhancement of brain tumour by contrast media in CT and MRI is due to open interendothelial junctions, fenestrae, gap junctions and increased pinocytic vesicles in the capillaries of these tumours 2 . However, it is not known whether the putative defect, which governs the development of edema, is the same as one, which causes contrast enhancement. It is also not known whether these two factors are related to each other or how they are related to the degree of damage to the BBB. The present study is aimed finding association between the volume of peritumoural edema and the degree of contrast enhancement in MRI of diffusely infiltrating astrocytomas. Material and methods: