The biochemical and behavioral effects of acute exposure to carbon monoxide (range 350 - 2000 ppm) are being studied in albino rats and pigeons. Biochemical studies in rats include measurements of surface PO2 and PO2 profiles of brain, heart and liver, and changes in concentration of ATP, creatine phosphate, lactate, pyruvate, beta - hydroxybutyrate and aceto-acetate (or glutamate, gamma - hetoglutorate, NH3) and in intracellular pH (CO2 method). A comparison will be made of the effects of equivalent reductions of HbO2 content produced by carbon monoxide, low inspired oxygen, and anemia. The behavioral studies have been directed toward the effects of interaction of carbon monoxide with drugs (barbiturates and amphetamines) in pigeons. Behavioral studies on rats are being planned.