in this paper, a DNA chip with a microelectrode array was fabricated using microfabrication technology. Several probe DNAs consisting of mercaptohexyl moiety at their 5'-end were immobilized on the gold electrodes by using a DNA arrayer. Then target DNA molecules were hybridized and reacted with Hoechst 33258, which is a DNA minor groove binder and electrochemically active dye. Linear sweep voltammetry or cyclic voltammetry showed a difference between the target DNA and the control DNA in the anodic peak current values. This difference was derived from Hoechst 33258 concentrated at the electrode surface through association with the formed hybrid. We suggested that this DNA chip can recognize the specific gene sequences. (c) 2005 Elsevier B.V. All rights reserved.