A flow through-type DNA array fabricated from an ideally ordered anodic porous alumina substrate is reported. Single-stranded probe DNA was affixed to file walls of the sub-micrometer-diameter holes, and fluorescently labelled target DNA was passed through the holes in the substrate. Fluorescence microscopy revealed an ordered array of fluorescent spots after the hybridization (see Figure), demonstrating the applicability of these porous alumina Substrates to fabrication of high-density DNA arrays.