A novel method for the extraction of HCV-RNA by using DNA probe coated-latex microparticle (AmpliTex) was developed. This high density particle, with a large surface area, could be dispersed uniformly in a guanidium lysate of the serum. The DNA probe on the particles could hybridize with a few copies of HCV-RNA in the lysate. The RNA thus extracted on the particle can be subjected to the reverse-transcription and PCR reaction. Analytical sensitivity to detect HCV in serum was approximately 20 copies per ml. AmpliTex and the conventional organic extraction gave the same sensitivity and specificity (both 100%) to detect the HCV-RNA from fifty clinical specimens. It was also possible to extract the HCV-RNA from heparinated plasma.