In the field of clinical genomics, pharmacogenic markers are being evaluated in order to discriminate between potential responders and nonresponders. In strategic alignment with the introduction of molecularly-designed drug candidates, the use of companion molecular diagnostic tests will help targeted drugs to achieve a greater therapeutic index. Realization of these potential advantages is evident from the increasing number of investigational new drug (IND) and new drug applications (NDA) as well as clinical study protocols that include tissue banking and pharmacogenic studies as integral component. An appraisal of critical issues and necessary steps to facilitate full integration of pharmacogenic tools in clinical development programs and medical care is presented. Expectation, promise, innovation, optimism are words which describe the enthusiasm for introducing pharmacogenic studies in the drug development process. The clinical utility of pharmacogenics to predict progression of disease or response to a drug therapy is a far reaching tool that will be added to treatment guidelines as part of the decision tree for evidence-based medicines. Veterans of the war on cancer are now eager to decipher the mysteries held within the human genome whose workings are subverted during the multiple steps that lead to oncogenesis. It is estimated that pharmaceutical companies will have 10,650 drugs in the pipeline by 2003 [101]. To evaluate the drugs in development in 2002, > 2.3 million people in the US participated in clinical trials [1]. The pharmaceutical industry drives the clinical development of drugs from Phase I through to Phase IV. However, both government agencies and pharmaceutical companies commission Phase I through to Phase III trials. In 2001, there were 750,000 trials funded by the government, with industry funding 850,000 trials in the US alone. In postmarket/Phase IV studies, industry dominated by funding 700,000 trials in the US. Oncology and AIDS/HIV drug therapy are the two areas where pharmacogenic markers have been successfully adopted as Food & Drug Administration (FDA)-approved molecular diagnostic tests. The worldwide cancer drug market, valued at US$30 billion, has doubled since 1998 and is rapidly expanding, with almost 400 cancerrelated drugs under development [101]. In oncology, there is an imperative to develop markers that apprise the physician and patient on whether to withhold therapies that might have serious adverse effects or treat with a specific drug that has the greatest possible benefit for the patient. Pharmacogenic studies are being integrated into every phase of drug development to select compounds with an assurance of safety. As a tool to eliminate failure early in development, pharmacogenic studies are valuable components of the drug development programme. Almost 80% of drugs fail due to safety concerns or poor efficacy. A review of pharmaceutical companies (1964–1985) reported that [2]: