Sensitive enzyme Immunoassay method specific for rabbit C-reactive protein was established. This was based upon specific Ca(2+)-dependent binding profile of C-reactive protein for some compounds containing phosphorylcholine moiety intramolecularly. By this method, more than 0.001μg of rabbit C-reactive protein was detectable. Specific binding of C-reactive protein for p-aminophenylphosphorylcholine immobilized on solid phase was inhibited by either addition of EDTA or phophorylcholine analogues, effectively. It may be useful to study possible roles of C-reactive protein in inflammatory regions.