Recombinant human erythropoietin has been used to treat anemia associated with chronic renal disease. This paper provides a comprehensive comparative analysis of Dynepo and three other commercial erythropoiesis stimulating agents, Eprex, NeoRecormon and Aranesp. We found significant differences in the type, levels and amount of O-acetylation of sialic acids. Sialic acids and O-acetylation present provide protection from clearance from circulation. Aranesp had up to six O-acetyl groups attached to the sialic acids. Eprex and NeoRecormon had only minor amounts of O-acetylation while Dynepo had none. Dynepo had no Neu5Gc, which is potentially immunogenic for humans. Dynepo contained the least amount of disialylated and Aranesp the highest amount of tetrasialylated glycans. NeoRecormon and Eprex contained more trisialylated, but less tetrasialylated glycans than Dynepo and Aranesp. Dynepo had the highest amount of tetraantennary glycans and the lowest amounts of triantennary glycans with a β1-6-GlcNAc linkage. All the samples contained poly-N-acetyl-lactosamine repeats with Dynepo having the least. The major N-acetyl-lactosamine extensions in Dynepo and Aranesp were on biantennary glycans, whereas in NeoRecomon and Eprex they were on triantennary glycans. The sLex epitope was only detected in Dynepo.