In this work a new type of the internal standard for the competitive RT-PCR is proposed: the RNA standard on the basis of the retrovirus vector. The internal standard has been developed for the qualitative and quantitative determination of hepatitis C virus RNA in patients' blood serum. The proposed internal standard consists of recombinant retrovirus particles in the culture medium of packing cells, containing the modified sequence of hepatitis virus C used for amplification in PCR. The presence of the selective marker--the gene of resistance to puromycin--in the vector makes it possible to determine the titer of virus particles of the standard in experiments of infecting cell cultures. The proposed retrovirus standard is obtained from the culture of packing cells by collecting the cultivation medium used for growing these cells. The virus particles thus obtained are not pathogenic for humans and animals.