A novel DNA biosensor based on oxidized graphene and polyaniline nanowires (PANIws) modified glassy carbon electrode was developed. The resulting graphene/PANlw layers exhibited good DPV current response for the complementary DNA sequences. The good electron transfer activity might be attributed to the effect of graphene and PANIw. Graphene and PANIw nanolayers film with highly conductive and biocompatible nanostructure were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The immobilization of the probe DNA on the surface of electrode was largely improved due to the unique synergetic effect of graphene and PANIw. Under optimum conditions, the biosensor exhibited a fast amperometric response, high sensitivity and good storage stability for monitoring DNA. The current response of the sensor increases linearly with the concentration of target from 2.12 x 10(-6) to 2.12 x 10(-12) mol l(-1) with a relative coefficient of 0.9938. The detection limit (3 sigma) is 3.25 x 10(-13) mol l(-1). The results indicate that this modified electrode has potential application in sensitive and selective DNA detection. (C) 2010 Elsevier Ltd. All rights reserved.