SummaryTo study the function of the 49 kDa excretory-secretory (ES) protein gene (P49) of Trichinella, the genes was amplified by RT-PCR from RNA of Trichinella spiralis and Trichinella nativa and several Chinese Trichinella isolates of domestic animals, and sequenced after being cloned. The amplified products of these parasites produced bands of about 950 bp. The 97.2 % to 100 % nucleotides identity and 94.3 % to 100 % identity of deduced amino acids among P49 gene of these Trichinella strains showed the close relationship of these parasites. The P49 gene of T. nativa was cloned into the BamHI site of the prokaryotic expression vector pET-30a, and the recombinant vector was expressed. The expressed product was 40.8 kDa in size. In Western blot analysis, the expressed product was reactive to sera of mice infected with T. nativa, T. spiralis and their Chinese geographical strains.