Only 15% of the waste blood generated in the Mexican meat industry is used for animal feed. However, waste blood is a slaughterhouse by-product that has potential for both animal feed and human food, because of its high protein concentration and quality. The aim of this work was to recover protein from red cells of bovine blood. Red cells were hydrolyzed with papain and up to 32% of the heme group released by this process, was separated by ultrafiltration. Treating the retentate with sodium hypochlorite produced a white product, which was 75% protein, nearly 1% ash, and almost tasteless. Results indicated that the protein contained in the white fraction had a good amino acid profile for use as an ingredient in formulated foods for human consumption.