Edema is the result of an imbalance in the filtration system between the capillary and interstitial spaces. The kidneys play a key role in regulating extracellular fluid volume by adjusting sodium and water excretion. Major causes of edema include venous obstruction, increased capillary permeability, and increased plasma volume secondary to sodium and water retention. A systematic approach is warranted to determine the underlying diagnosis. Treatment includes sodium restriction, diuretic use, and appropriate management of the underlying disorder. Leg elevation may be helpful in some patients. Loop diuretics often are used alone or in combination. In patients with New York Heart Association class III and IV congestive heart failure, spironolactone has been found to reduce morbidity and mortality rates. In patients with cirrhosis, ascites is treated with paracentesis and spironolactone. Dihydropyridine-induced edema can be treated with an angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker. Lymphedema occurs when a protein-rich fluid accumulates in the interstitium. Compression garments and range-of-motion exercises may be helpful in patients with this condition.