Cardiovascular drugs are characterized by wide inter-individual variability in dose/plasma concentration/ response (therapeutic and/or toxic) relationships. Therefore, some patients achieve good therapeutic response to their drug therapy, while others do not. Also, some patients experience adverse effects, which vary from mild to life-threatening. The source of variability in patients' response to cardiovascular drugs may be of pharmacokinetic and/or pharmacodynamic origin. Many factors can potentially affect both of them such as genetics, gender, age, disease state, environmental factors like smoking and food, possible drug-drug interactions, and ethnicity (race). Cardiovascular pharmacogenomics is a new field that focus on the roles of genetic polymorphisms in drug metabolizing enzymes and drug targets in development of variable drug response.