Abstract: AIM　To synthesize fragments of inhibin subunits βB(1-28) (GLECDGRTNLC-CRQQFFIDFRLIGWNDW), βB(85-115) (LSTMSMLYFDDEYNIVKRDVPNMIVEECGCA) and to obtain their monoclonal antibodies. METHODS　Two segments of inhibin βB subunit were synthesized as semiantigens by solid phase peptide synthesis with Fmoc chemistry. These peptide products were conjugated with TG as antigens to prepare McAbs against inhibin βB subunit while EDC was coupling reagent. After immunization, fusion, selection and cloning procedures, 4 hybridoma cell lines were obtained. Ascites titer, specificity and relative affinity were identified. Four hybridoma cell lines were obtained through preparations of immunogens and monoclonal antibodies. The analysis of these McAbs indicated that they were highly special, sensitive and practical. The McAbs of inhibin α, βA and βB subunits were further purified. The immunohistochemistry in breast cancer was carried out with these three subunits′ McAbs. RESULTS　The McAbs of inhibin βB subunit were highly sensitive, specific and useful. There was no notable divergence on the reactions of relative tumor tissues to the McAbs of inhibin α, βA and βB subunits in immunohistochemistry study. There was also almost the same positive ratio of the reaction of breast cancer tissues to these McAbs. CONCLUSION　The method of detecting serum inhibin level will be established on the basis of present research.