New gene targets for disease susceptibility and therapeutic intervention only provide a starting point in the long and difficult process of incidence of a particular disease and drug discovery. The incorporation of genetic information into the routine prescribing of drugs may become standard to avoid serious toxicity with narrow therapeutic index drugs, and to maximize the likelihood of a positive response in the individual patient. However, genomics and genetic variations in particular amongst individuals will have an important impact in understanding of the molecular nature of diseases and of the responses, both desirable and adverse to drugs. Modern genetics will bring about significant improvements in the provision and practice of healthcare by redefining disease and targeting treatment. It will also lead to the discovery of novel targets and effective treatments and the provision of more effective preventative healthcare. Pharmacogenomics aims to complement the current ‘one-medicine fits-all’ scenario with drugs that are based on a deeper understanding of gene variations and the effect of such variations on drug responses.