The risk of pial or brain injury while dissecting the cerebral cistern to treat acute subarachnoid hemorrhage might be higher than that of unruptured aneurysms, because visualizing the arachnoid trabeculae between the pia mater and the vessels can be complicated by thick subarachnoid clots filling the cerebral cistern. The author describes technical points of dissecting the cerebral cistern and the removal of subarachnoid hematomas during acute surgical treatment for subarachnoid hemorrhage. Tough arachnoid trabeculae form a "perivascular cistern" around the relatively major vessels in both the sylvian and interhemispheric fissures. The cistern can be separated without pial injury by identifying the microstructure surrounding the major vessels in the cistern and then cutting the arachnoid trabeculae. After bloodless dissection of the cistern, the subarachnoid hematoma can easily be irrigated and removed. The subarachnoid clot must be repeatedly irrigated by flushing the micro-space between arachnoid trabeculae with jets of water to ensure efficient removal. When the arachnoid trabeculae become transparent, small vessels and the arachnoid trabeculae can be differentiated as well as whether or not they can be cut. To treat sylvian hematoma, subpial hematomas extending from the insular cistern and intra-cisternal clots must be removed. Furthermore, inducing complete hemostasis by coagulating the subpial vessels is indispensable to prevent postoperative rebleeding.