Objectives: Glycophorins A (GPA) and B (GPB) are the major sialoglycoproteins of the human erythrocyte (RBC) membrane. To prepare tools for the analysis of GPA and GPB, we produced a series of new monoclonal antibodies (mAbs) that identified epitopes of GPA. Methods: Seven murine monoclonal antibodies directed to glycophorin A (GPA) were fully characterized by agglutination of untreated and enzyme-treated human erythrocytes, inhibition of agglutination using chemically modified glycophorins and peptides from GPA, immunoblotting, and binding to synthetic peptides on plastic pins. Results: The antibodies identify epitopes located on four different portions of GPA: (1) NaM13-6D2 binds to the N-terminal portion of GPA and GPB carrying the N blood group antigen; (2) NaM26-3F4 recognizes the homologous portion of GPA and GPB corresponding to their amino acids 6-26; (3) NaM10-2H12, NaM16-IB10 and NaM10-6G4 are specific for the amino acid sequence 38-45 of GPA; and (4) NaM37-5F4 and NaM13-4E4 bind to the amino acid residues 119-124 located on the intracellular ponion of GPA. Conclusion: These antibodies represent precise tools to investigate GPA and related molecules in different cells and tissues.