There is now an increasing trend towards personalized medicine in which factors specific to an individual patient are taken into consideration to provide individualized care. One of these is the need to determine the metabolic status of an individual when using drugs, the actions of which are influenced by drug-metabolizing enzymes. The AmpliChip CYP450 test is a microarray molecular diagnostic test to determine how the body may break down medications. It analyses Cytochrome P450 enzyme system and its variants, particularly CYP2D6 and CYP2C19, which play a role in the metabolism of approximately 25% of all drugs prescribed to patients. The test result can categorise individuals into one of 3 groups – a) intermediate or poor metaboliser (patient may experience toxic effects of overmedication while taking a standard dose and may benefit from smaller doses of the medication); b) ultra-rapid metabolisers (patient may not respond to a standard dose of medication as they metabolize certain drugs so quickly that the blood concentration of the medication may never reach optimum therapeutic levels needed to achieve the desired effect. Hence, these patients may benefit from increased doses of medication); and c) extensive metabolizers (patient normally metabolises drugs given within a standard dosing schedule and would have an expected response to medication similar to that of the majority of people within a given population). The test kit manual lists a large number of drugs metabolized by this system including antidepressants, antipsychotics, immunosuppressive and anticancer drugs. This helps the doctor to select a particular drug and its dose for an individual patient. But the test alone cannot decide the drug dose but is meant for use along with clinical evaluation and other methods for the selection of the treatment that is best suited for an individual patient.