The effect of experimental anaemia induced by phlebotomy and the effect of infusion of various fluids on the 2,3-DPG, ATP and total organic phosphate (Porg) concentration were examined in the red cells of beagles made anaemic by withdrawal of 30% of the circulating blood. Particular groups of dogs 30 min after phlebotomy were infused with own blood, blood with inosine, pyruvate and phosphate (IPP), Fluigel and Fluigel with IPP. The changes were most distinct in dogs which were not infused with any fluid. After 24 hours the content of 2,3-DPG, ATP and Porg increased by 17, 27 and 20%, respectively, in comparison with the results obtained before blood loss. Twenty-four hours following the reinfusion of own blood, a slight increase occurred in the 2,3-DPG and Porg content. Infusion of Fluigel caused a decrease of the phosphate compounds concentration after 3 and 6 hours and then the concentration almost returned to normal. Infusion of own blood as well as Fluigel enriched with inosine, pyruvate and phosphate did not lead to any change in 2,3-DPG concentration. The red cells of dogs do not utilize inosine for 2,3-DPG or nucleotide synthesis. The increased cardiac output seems to the main mechanism for oxygen transport to tissues after an acute haemorrhage.