Cardiovascular diseases in general have been a high risk for most of deaths in the world. The selection of appropriate medications to minimize and or diminish the signs and symptoms of cardiovascular are always a concern of medical staffs. Among all the available cardiovascular drugs in the market, diuretics have been studied and used in decades. The effect of diuretics is based on their site of action at nephron. Based on their mechanism of action mainly on the inhibition of sodium reabsorption, their natriuretic effect is useful in most case of edematous conditions. To use diuretics appropriately for treatment of different conditions, we have to determine the renal function of patient and or dosage adjustment for different conditions. This can be done by the study of pharmacokinetics as well as pharmacodynamics of diuretics. Using diuretics for treatment of hypertension and heart failure is the mainstay. The phenomenon of diuretics resistance is defined as the decrease of effectiveness of diuretics in heart failure, and the management of this condition will be discussed further.