Hemorrhagic shock was produced in conscious rats by cannulating the subclavian artery and bleeding the animals to a mean arterial pressure of 40 mm Hg which was maintained for 1 (early shock) or 2 hr (late shock). Analysis of tissues showed that there was a significant decrease in ATP and ADP levels in liver and kidney in early and late shock. Associated with the decrease in ATP and ADP levels were increases in AMP and P(i) levels. In contrast to the above organs, adenine nucleotides and creatine phosphate levels of skeletal muscle did not decrease in early shock but a significant reduction of these sompounds was observed in late shock. The decrease in ATP content was greater in liver and kidney than in skeletal muscle. The present experiments indicate that there is a decrease in the energy available to tissues during severe hemorrhagic shock. This could be due to decreased biosynthesis, to continuing or increased utilization of the nucleotides, or to both.