Phosphorylation and dephosphorylation of tyrosine residues of intracellular proteins are an important cellular regulatory mechanism, involved in processes such as cell growth, proliferation and differentiation. The regulation must involve a careful balance of the two groups of enzymes; PTKs (protein tyrosine kinases) and PTPs (protein tyrosine phosphatases). To study the role of dual-specificity tyrosine phosphatase in the chicken embryo development, new PTP genes was cloned from the chicken embryo cDNA library. Two degenerate primers, which were encoded highly conserved regions of dual-specificity tyrosine phosphatases were designed. Polymerase chain reaction (PCR) were performed to amplify the putative dual-specificity tyrosine phosphatase gene using the degenerate primers from chicken embryo cDNA. A partial gene fragment, analogue of human CL100, was obtained and we have screened its full gene by in situ plaque hybridization method in the chicken embryo cDNA library. Some clones showing positive signals were obtained after many screening steps. The candidate clones were analyzed by nucleotide sequencing and deduced the amino acid sequence. The 960bp fragment is 86% and 84% identical with human CL100 and rat 3CH134, respectively and it has a PTP catalytic domain (CxxxxxR). The 300bp fragment is 66% homologous with human CL100 mRNA 3``UTR. The results of alignments were shown that around the catalytic domain, about 160 amino acids were highly conserved and secondary structures were also conserved.