Beginning with 1975, our group has performed some studies using an erythropoietin (EPO ) extract prepared according to an original technique from sera of anemic rabbits. Our results have contributed to the understanding of the glycoproteinic nature of this extract as well as of some of its biological features. These results were confirmed only after 1985, when recombinant EPO was obtained. The aim of this study is to emphasize some of our priorities, controversial at that time. We have shown the radioprotective effect of an EPO extract, in correlation with red cell proliferation and with an increased rate of nucleic acid metabolism and bone marrow blood flow. Consequently, we proposed the investigation of the bone marrow function using EPO. Our results are correlated with recent data obtained with recombinant EPO. They refer to the ability of EPO to prevent apoptosis, its antioxidant effects, and its ability to modulate the sympathoadrenal response to hypoxia.