Hypertension is a major public health problem often leading to cardiovascular, cerebrovascular and renovascular problems. It has a cause effect relation with increased oxidative stress. Increased ROS can further cause damage to macromolecules of the cell like proteins, lipids and DNA. Damage to DNA can result in malignancies whereas the genetic polymorphism in metabolic enzyme genes can further alter the levels of oxidative stress. This book explores the review of clinical studies on human samples regarding genetic damage, oxidative stress and genetic polymorphism of drug metabolizing genes in hypertensive patients.