Histochemical studies have been carried out to evaluate the effect of evacuation of hematoma in the case of the hypertensive intracerebral hemorrhage and also the effect of oral administration of pyridinol-carbamate in such surgical procedure. Experimental renal hypertension of 34 male rabbits was made by Goldblatt's method, 12 rabbits were dead for hypertensive condition, including a rabbit with massive intracerebral hemorrhage. Normal 4 rabbits were used as control group. Artificial intracerebral hematoma was made in 18 hypertensive rabbits by injection of 0.3ml of venous auto-blood into the area of the internal capsule through a small burr hole stereotaxically. The hematoma were evacuated by insertion of 18 gauge needle 3 days after the blood injection. The results were as follows: a) Rabbits of experimental hypertensive intracerebral hematoma were divided into two groups; 5 rabbits medicated with pyridinol-carbamate of 30mg/kg B.W. for about 9 weeks preoperatively and 4 non-medicated rabbits. In the non-medicated group, enzymatic activities of LDH of Embden-Meyerhof pathway, SDH and MDH of TCA cycle, Cy-O of the electron transport system and also Al-p, Ac-p of the hydrolytic enzymes were diminished in the adjacent area of the hematoma. This indicated the considerable decrement for maintenance of metabolism, tissue respiration and the cell function in that area. In contrast, G-6-PDH of Warburg-Dickens pathway was accelerated in the cortex. It suggested that hexose-monophosphate shunt was playing an important role of metabolism in this pathological conditions. These enzymatic activities of medicated group showed also similar pattern to that of nonmedicated group. They showed, however, rather minimum changes. b) In 9 rabbits with hypertensive intracerebral hematoma, the hematoma were evacuated afterwards. These rabbits were also divided into two groups; 5 medicated with pyridinolcarbamate and 4 non-medicated rabbits. In the non-medicated group, LDH, SDH, MDH activities as well as Ac-p and Al-p activities were decreased in the adjacent cerebral tissue of the evacuated hematoma. However, Cy-O activity showed almost normal. This indicated that extirpation of the blood-clot was effective for the restoration of the destructed blood brain barrier and the disturbed metabolism in the cerebral tissue. In the medicated group, these all enzymatic activities showed almost normal in that area. These results suggest for us that the surgical evacuation of intracerebral hematoma is a choice of treatment and that the preventive medical treatment such as oral administration of pyridinol-carbamate should be combined with the surgical management under these hypertensive condition.