Pharmacogenomics is the study of genomics/genetics and proteomics. It is the field of science which can make the goal of personalised medicine possible. This review article briefly explains about various genes associated with therapeutic activity of various Anti-cancer and Anti-reteroviral drugs in humans. The need to perform PGx test to find the ADR’s of these drugs and narrowing of these drugs which are used for the treatment of these diseases especially during their lethal stages . this is an critical review on why same drugs in same doses have different effects in different persons and how this field has been used in various health care systems over the period of time was described. This presentation also emphasizes the scope of pharmacogenomics in improving health care system.