In the present study, we obtain a mouse anti-porcine complement receptor type 1 (CR1)-like monoclonal antibody (McAb) and use this McAb to verify the existence of CR1-like protein on porcine erythrocytes. Our results confirm that CR1-like protein is localized on the surface of porcine erythrocytes. Mouse immunoglobulin G inhibited the binding of serum-opsonized green fluorescent protein-expressing Escherichia coli to porcine erythrocytes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis indicates that CR1-like McAb reacts with biochemically-purified porcine erythrocyte membrane fractions, with a clear band at 135 kDa to 140 kDa. We postulate that the 135 kDa to 140 kDa membrane protein is the equivalent of the porcine erythrocyte CR1-like protein.