The human cytomegalovirus (HCMV)glycoprotein 52 kD gene was cloned and the DNA sequence of antigenic domain of this gene was amplified with polymerase chain reaction (PCR) technique. The sequences of oligonucleotide primers are 5'-AAAGAATTCATGAACGTGAAGGAATCG-3'(upstream primer) and 5'-ATAAAGCTTAATTCAGACGTTCTCTTCTTC-3'(downstream primer). The PCR product was purified and digested with EcoR 1, and then inserted into the EcoR Ⅰ digested expression plasmid pBV-220. The cloned gene was expressed under control of the hybrid P_RP_L promoter in E.coli following induction at 42℃ for 2h, 4h and 6h, respectively. The proteins in the lysate of bacteria were analysed by using 12.5% SDS-PAGE. The predicted protein 13kD expressed from the cloned gene in E.coli was observed and harvested. Up analysing the antigenic domain of HCMV glycoprotein 52 kD, a polypeptide in length of 25 amino acids was synthesized, of which sequence is Phe-Asp-Leu-Glu-Glu-Ile-Met- Arg-Glu-Phe-Asn-Ser-Tyr-Lys-Gln-Arg-Val-Lys-Tyr-Val-Glu-Asp-Lys-Val-Val. The expressed protein and synthetic polypeptide were used to immunize rabbits respectively, and two kinds of antisera reacted with the expressed antigen and HCMV AD 169 antigen detected by using ¹²⁵I-labelled protein A. The results of Dot-blot and Western transfer show that the protein expressed from the cloned gene has the same band in size and specificity of antigen as those of the synthetic poly-peptide. By using horse radish peroxidase (HRP) labelled IgG instead of ¹²⁵I-protein A, preliminary result indicated the diagnostic value of the expressed protein and its antiserum for the HCMV infection.