Male dogs were anesthetized with endotracheal anesthesia under the normal and the artificial hypotensive blood pressure and the influences of the anesthesia on the nucleic acid metabolism in the liver and the kidney were studied. 1) No marked degenerative changes were generally observed in both normal and hypotensive groups by anesthesia. 2) The influences on the nucleic acid metabolism were very slight in both groups. 3) In the hypotensive group, dilatation of the capillary vessels in the kidney and liver was observed. 4) The changes of R.N.A. seemed a little greater than those of D.N.A. in both groups, but no definite tendency was hardly observed. 5) Histological changes including the change of nucleic acid seemed stronger as the duration of anesthesia became longer and the grade of hypotention became greater. However, no marked difference observed between 2 and 3.5 hours of anesthesia and between 20% and 40% of hypotensive rate.