Intracerebral hematoma was experimentally produced by injection of arterial auto-blood into the area of the internal capsule with stereotaximetry in dogs.Forty-eight hours after injection of blood the hematoma was aspirated, and the aspirated and the non-aspirated cases were studied histologically and histochemically.The animals were sacrificed after one week to two months, and surrounding tissue of intracerebral hematoma was histologically and histochemically studied.The activity of succinic, lactic, malic, α-glycerophosphate, and glutamic acid dehydrogenase in nerve cells was markedly decreased in areas surrounding the hematoma even after two months in non-aspirated cases, while it was well preserved in aspirated cases.According to the above results, it was ellucidated that the aspiration of hematoma content was effective on the prevention of degeneration of nerve cells caused by hematoma.