A monoclonal antibody (MAb) specific for chicken interleukin-6 (chIL-6) was generated by using Balb/c mice immunized with recombinant chIL-6 (rchIL-6). On Western blot analysis, the MAb, designated E3, reacted with rchIL-6 but not with recombinant murine IL-6 (rmIL-6). The MAb E3 also reacted with supernatant of the chicken macrophage-like cell line HD11 stimulated with lipopolysaccaride. The rchIL-6-induced phosphorylation of STAT3 in a chicken hybridoma cell line was inhibited by addition of MAb E3 in a dose-dependent manner. These results indicate that the MAb E3 specific for chIL-6 is useful for detection and functional analysis of chIL-6.