The leukocyte-associated Ig-like receptor 1 (LAIR-1), an inhibitory receptor bearing two immunoreceptor tyrosine-based inhibitory motifs (ITIM), is expressed on the majority of peripheral leukocytes, including NK cells, T cells, B cells, monocytes, dendritic cells, granulocytes, and thymocytes and is involved in immunologic regulation and hematopoiesis. Murine LAIR-1 (mLAIR-1) is the homolog molecule of human LAIR-1. Using mLAIR-1-Fc as the immunogen and the technique of rat B lymphocyte hybridoma, we raised three hybridoma cell lines secreting monoclonal antibodies (MAb) to mLAIR-1, designated FMU-mLAIR-1.1, -1.2, and -1.3. Rat immunoglobulin class and subclass of the MAb FMU-mLAIR-1.1 approximately 3 were determined to be IgM, IgG1, and IgM, respectively. All these MAbs can bind the mLAIR-1 in immunocytochemistry and immunohistochemistry. FMU-m LAIR-1.2 worked well not only in Western blot assay but also in recognizing natural LAIR-1 molecules on the surface of P388D1, J774, and WEHI3 cells, and mLAIR-1 cDNA-transfected CHO cells detected by FCM. Thus, successful production of rat anti-murine LAIR-1 monoclonal antibodies provides a new powerful tool for investigation of murine LAIR-1 function in mouse model, both in vitro and in vivo.