This review discusses the role of diuretics in heart failure by focusing on different classifications and mechanisms of action. Pharmacodynamic and pharmacokinetic properties of diuretics are elucidated. The predominant discussion highlights the use of loop diuretics, which are the most commonly used drugs in heart failure. Different methods of using this therapy in different settings along with a comprehensive review of the side-effect profile are highlighted. Special situations necessitating adjustment and the phenomenon of diuretic resistance are explained.