Models have been devised and characterized in the laboratory rat for studying the neuropathology of subarachnoid hemorrhage. Several ways of injecting blood via different routes have been tried; cortical subarachnoid administration is the most reproducible suitable model. The location of injected blood was detected in histological sections. In this rat model for subarachnoid hemorrhage, the arterial blood pressure and the intracranial pressure did not elevate significantly, and the influence of major ischemic components in the development of brain edema could also be ruled out. Measurements performed on the water, electrolyte, and albumin contents of brain tissue have clearly indicated that the brain edema developing in the acute stage of rat experimental subarachnoid hemorrhage could be classified as having a primarily vasogenic component as well. These findings may have implications in the treatment of subarachnoid hemorrhage.