FCRLA is a recently identified intracellular protein structurally related to the classic Fc receptors and expressed primarily in the germinal centers of B cells. We generated six monoclonal antibodies (MAbs) specific to the human protein. The MAbs recognize three different epitopes, which were shown to be localized on the D3 domain of the FCRLA molecule. The clones M101 and M616 were demonstrated to be applicable in various immunochemical analyses, such as immunoblotting, immunohistochemistry, and immunoprecipitation. In addition, this pair of antibodies was used for development of a sandwich version of ELISA to quantitatively detect FCRLA in cell lysates. Using these MAbs, we studied FCRLA expression in a panel of human B cell lines, such as Raji, Daudi, Bjab, BL-2, RPMI 1788, RPMI 8226, IM-9, and SKW6.4. It was found that all these lines, except RPMI 8226, produce FCRLA but may vary in the proportion of FCRLA-positive cells. The MAbs we established can be a useful tool to investigate the functional role of FCRLA and its applicability as a B cell development and malignant transformation marker.