This repport aims to demonstrate the value of the venous phase, in sagittal incidence, for the angiographic diagnosis of subdural hematoma. It is based on eight such cases, all of them with surgical confirmation. Six of the patients had unilateral hematomas and the remaining two had bilateral blood collections. Ten subdural hematomas were, then, diagnosed by means of cerebral angiography. In only one instance the elliptical non vascularized area which constitutes the pathognomonic sign of the above referred nosological entity could be seen, under frontal projection, right in the arterial phase. In the other cases the specific diagnosis of subdural hematoma would not be achieved if the venous phase had not been taken in account. The arterial displacement seen in most cases of subdural hematoma gives no help for specific diagnosis; such a displacement may occur in any case of space-occupying lesion. Besides, existence of subdural hematomas with no arterial dislocation, is a known condition, mainly in that cases of bilateral subdural blood collections. On the other hand a single, unilateral hematoma with no shifting of the anterior cerebral artery to the opposite side is also suitable. In the last three cases of this series, there was no significant displacement of the anterior cerebral artery; the venous phase, in antero-posterior incidence, and further surgical exploration, showed the hematomas to be bilateral in two; in the third of these cases the anterior cerebral artery had a normal course, in spite of the space taken by a single hematoma. Thus, if the venous phase shows the characteristic picture of subdural hematoma - avascular area - with no displacement in the arterial phase, it does not mean necessarily that the hematoma is bilateral. Nevertheless angiography on opposite side must always be done. Since in angiographic diagnosis of subdural hematoma the accuracy of the venous phase, in sagittal projection seems to be proven, we think that the above mentioned step of the examination has to be done even if, in order to achieve it, a new injection of contrast may be required.