Hyperbaric oxygenation (2 atm O2, 40 min) accelerates the restoration of the normal cell count and hemoglobin concentration in the peripheral blood of albino rats after acute blood loss (2.8% of body weight). In the bone marrow, coupled with increased proliferative activity of erythroblasts and normoblasts, intensive maturation of hemoglobin-containing forms was observed. The maximal level of plasma erythropoietic activity of the anemized animals was found on the first and tenth days after blood loss. The serum possessed erythropoiesisinhibiting properties on the 15th day. It is postulated that hyperbaric oxygenation after acute blood loss potentiates the stimulation of erythropoiesis induced by erythropoietin.