The author analyses the lesions of carotid artery wall in the Guinea pig (Cavia porcellus) submitted to temporary clipping with clips used in microvascular neurosurgery, by means of intravital injection of gelatin and India ink to contrast the vasa vasorum. The arteries were cleared with xilol and observed on the optic microscope and later throught histologic sections. Acute lesions without relationship to the clipping time were verified in the intima, tunica media and in the vasa vasorum network of the adventitia. The results suggest that there is a critical clip pressure, above that there is no direct relationship between the clip pressure and the severity of the lesion of the arterial wall. The arteries observed 30 days after the temporary clipping showed a partial recuperation relative to the acute lesions, although alterations in the intima and tunica media persisted and will constitute weak points in the arterial wall. Differences relative to the clip pressure were not observed in the acute severe alterations of the vasa vasorum and in the later reactional picture showed by these vessels. It was not possible correlate the severity of the lesions of the arterial wall and the alterations of the vasa vasorum. It is believed that the mechanical trauma due to clip pressure was more important than the ischemia in the genesis of these lesions. Despite the severity of the lesions observed in the arterial wall submitted to temporary clipping, thrombosis and vascular occlusion were not observed in the studied animals.