Abstract: Rabbits’ livers were irradiated by focused ultrasound at the intensity of 30 W/cm², frequency 1.06 MHz, for 3 mins. directly. The treated animals were sacrificed at 1 day, 3 days, 7 days, 1 month and 2 months after irradiation. Then the irradiated area of the liver was cut off and studied with routine histological H. E. method and some histochemical techniques, including the demonstration of adenosine triphosphatase （ATPase）, thiamin pyrophosphatase （TPPase）, nonspecific esterase （NSEase）, succinate dehydrogenase （SDHase）, and glycogen. The histological and histochemical changes in this experiment are as follows:
（1） The cavitational vesicles which are produced in the cytoplasm of light lesion hepatic cell, squeeze the nucleus to margin of the cell, and extend the contour of hepatic cell to a ball-shape appearance. All the ball-shape cells in the hepatic cord decrease their contact surface and are apt to separate from one another.
（2） The activities of ATPase, TPPase, NSEase and SDHase in the heavy lesion cells decrease vigorously, even no activities can be seen. Such phenomenon repesents necrosis of these cells.
（3） The reactions of ATPase, NSEase and SDHase in the light lesion cell are stronger than that of normal cells. It seems to be the result of a feedback of lesion.
（4） The slight decrease of the activity of TPPase in the light lesion cells indicates that the cells retain the function of bile secretion.
（5） Glycogen granules disappear both in light and heavy lesion regions.