The DNA microarrays have proven to be a state of the art technique for high throughput comprehensive analysis of thousand of genes in parallel. The application of a DNA microarray to compare normal and pathological cells, tissues or organs may allow, along with classical positional cloning techniques, to speed up the discovery of genes and gene pathways implicated in several diseases. This in turn will result in further application of the DNA microarray technique in the field of pharmacogenomics in order to characterize and validate new therapeutic targets, their mechanism of action, metabolic pathways and unwanted secondary effects. However, the lack of standardized criteria for the analysis and interpretation of the huge amount of data generated by DNA microarrays may hamper its utilization on a routine basis in the human health domain.