Phage-displayed random peptide libraries have become an efficient tool for epitope mapping. We used a 6-mer library displayed on PIII of fd phage to screen for the epitope of tumor necrosis factor(TNF-alpha) by monoclonal antibodied. Three rounds of biopanning have been carried out and dot blot and ELISA were used to estimate the enrichment. Seventeen clones from the third rounds of biopanning were randomly selected and the insert DNA sequences were determined. Based on the deduced amino acid sequences, the motifs, LHPGIL and LHPGVC, have found to show homology with TNF-alpha. Finally, the binding inhibition tests proved that binding of antibody (T(5)McAb) was competitively inhibited by phage-borne HLPGIL.