The pharmacogenetics is one of the most promising fields of medicine. The conclusion of the Genome Project allowed this field to start discovering complex factors modulating the response to drugs, and new technologies are close a great expansion of the area. The cardiovascular diseases are currently among the major causes of hospitalizations and death, and have been the target of a large part of genetic studies of complex diseases. Parallel to the susceptibility to disease markers identification, it is necessary to investigate how different genetic profiles can change the responses to the currently used drugs. The biological system that controls the endothelial production of the nitric oxide has been one of the greatest targets in the pharmacological responses to the drugs used in the cardiovascular diseases therapy. This review aims at approaching the current knowledge on interaction among the genetic variations of eNOS and the pharmacological responses to the drugs used in the cardiovascular system.