As riboflavin carrier proteins play a critical role in the maintenance of pregnancy, studies on the immunology of these proteins have become very relevant. This paper describes our attempts to identify the sequential antigenic determinants of chicken riboflavin carrier protein (cRCP). Potential surface oriented regions of cRCP were identified by constructing acrophilicity and hydrophilicity profiles of the protein. Of the three regions identified, the pentadecapeptide 10-24 of cRCP forms the subject of the present study. The pentadecapeptide amide was synthesized by solid phase synthesis using Fmoc chemistry. Immunization of rabbits with the peptide-diphtheria toxoid conjugate elicited high titres of the antipeptide antibodies, revealing the high immunogenicity of the peptide. The antipeptide antibodies bound to both cRCP and reduced carboxymethylated RCP (RCM-RCP). Antisera to RCM-RCP showed significant binding to the peptide showing thereby that the region 10-24 of cRCP is perhaps one of the major epitopes of RCM-RCP. Thus, the studies have resulted in the identification of the region 10-24 as an antigenic determinant of cRCP.