Human synovial mast cells (MC) can be immunolabelled with antihuman CXCR3 antibody (Ab) (clone 49801). We have investigated whether cutaneous and mucosal MC are stained with anti-CXCR3 Ab in paraffin-embedded sections. Immunohistochemical staining and immunofluorescence double staining assays were performed with anti-CXCR3, anti-tryptase, and anti-chymase Ab using normal skin, psoriatic skin lesions, and normal colon. When compared with tryptase and chymase staining, 100% of the cutaneous and 98% of the mucosal MC were positive for CXCR3. Anti-CXCR3 staining is a useful marker for human cutaneous and mucosal MC in paraffin-embedded sections.