DNA microarray is a powerful tool allowing simultaneous detection of many different target molecules in one sample. The efficiency of the array mainly depends on the sequence of the capture probes and the way in which they are attached to the support. Coupling process needs to be quick, reproducible and compatible with automatic spotting devices dispensing tiny drops of liquid on the glass surface. Coupling strategies were evaluated in light of grafting DNA onto the glass surface. The results indicate that attaching unmodified DNA to a poly-L-lysine coated glass surface is a preferred method in fabricating DNA microarrays. In this paper, both the coupling procedure and the hybridization efficiency have been optimized. The unmodified double-stranded DNA in high salt solution being spotted onto the poly-L-lysine coated glass surface enhances the adsorption of DNA onto the poly-L-lysine layer.