To evoke anoxic anoxia 5 vol % oxygen was inhalated. under 2.5% Ravonal anesthesia, to adult healthy dogs, to dogs whose reticuloendothelial system had been blocked and to bilaterally adrenolectomized dogs. After that, blood coagulation time, plasma coagulation time after calcium readdition, prothrombin index, plasma fibrinogen content and blood water content were measured during pure oxygen inhalation as well as 15, 30, and 45 minutes after commencement of anoxia for a comparative study. 1. Blood coagulation time reduced rapidly in normal dogs with development of anoxia. The reduction was slight in dogs with blocked reticuloendothelial system and almost none in bilaterally adrenolectomized dogs. 2. Plasma coagulation time after calcium readdition reduced in healthy dogs with development of anoxia. An almost similar reduction was observed in dogs with blocked reticuloendothelial system. In bilaterally adrenalectomized dogs, however, it was slight in extent. 3. Prothrombin index increased slightly with development of anoxia except in bilaterally adrenolectomized dogs in which the increase was insignificant. 4. Plasma fibrinogen content increased with development of anoxia in any case. The increase was greater in dogs with blocked reticuloendcthelial system than in normal dogs both during pure oxygen inhalation and during anoxia. With bilaterally adrenolectomized dogs, no difference was noticed compared normal dogs. 5. Blood water content decreased with development of anoxia. No influence of blocking of the reticuloendothelial system or bilaterally adrenolectomy was observed.