Oligo microarrays or DNA chips are the ultimate experimental tool for research, drug discovery and diagnostics. They have the potential to perform a variety of molecular assays simultaneously and to generate a wealth of information from a single clinical sample. A DNA microarray consists of a solid support to which unique nucleic acid sequences (probes) are attached at specific positions. Nucleic acid hybridization is the central event in an oligo microarray. Sequences from a labeled target are recognized by the hybridization affinities of the oligonucleotide probes in a highly specific and sensitive manner.