This work describes the development of a genosensor for the detection of the hepatitis C virus (HCV) in real samples. Gold electrodes were modified with graphene oxide functionalized with ethylenediamine (GO-ETD) for the immobilization of a HCV specific probe. HCV infected sera and viral genomic RNA were evaluated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). EIS measurements showed an increase of about twice in charge transfer resistance values, after addition of HCV genomic RNA. In the DPV analyses, the genosensor was able to discriminate HCV positive serum samples from HCV negative serum, with a difference of 3 times between these samples. It was observed an inverse linear relationship between the values of the peak current of the ferrocyanide ion oxidation and the concentration of the samples. The detection limit was 1:483 (v/v) or 1.36 nmol.L-1 of RNA. The developed genosensor enables a selective and specific diagnosis of hepatitis C.