Objective To express the hepatitis C virus (HCV) core gene in E . coli on a high level. Methods The cDNA coding for HCV core protein was amplified by polymerase chain reaction (PCR). The PCR product was purified and digested with restriction enzymes and inserted into the downstream of P RP L promoter of a high level expression vector pBV220 . HCV core gene was expressed in E . coli in a non fused form. The expression protein was analysed by SDS PAGE , and its immunoactivity was tested by ELISA . Results Sequence analysis of the amplified PCR products confirmed that we have successfully cloned and expresssed the intact core protein of HCV. SDS PAGE showed that a specific protein with a molecular weight of 21kDa at a level of 14.0% of the total bacterial proteins appeared in bacteria harboring pBV/HCVCore, while this protein was absent in the control bacteria harboring pBV220. The results of enzyme immunoassay analysis showed that this protein could be specifically recognized by the HCV positive sera from patients with hepatitis C .Conclusion The intact HCV core protein was successfully expressed in  E . coli  in a non fused form on a high level, and its immunoactivity was high. Methods The cDNA coding for HCV core protein was amplified by polymerase chain reaction (PCR). The PCR product was purified and digested with restriction enzymes and inserted into the downstream of P RP L promoter of a high level expression vector pBV220. HCV core gene was expressed in E. coli in a non-fused form. The expression protein was analyzed by SDS PAGE, and its immunoactivity was tested by ELISA. Results Sequence analysis of the amplified PCR products confirmed that we have successfully cloned and expressed the intact core protein of HCV. SDS PAGE showed that a specific protein with a molecular weight of 21 kDa at a level of 14.0% of the total bacterial proteins The results of enzyme immunoassay analysis showed that this protein could be specificall y recognized by the HCV positive sera from patients with hepatitis C. Confluenced The intact HCV core protein was successfully expressed in  E. coli  in a non-fused form on a high level, and its immunoactivity was high.