Peripheral edema often poses a dilemma for the clinician because it is a nonspecific finding common to a host of diseases ranging from the benign to the potentially life threatening. A rational and systematic approach to the patient with edema allows for prompt and cost-effective diagnosis and treatment. This article reviews the pathophysiologic basis of edema formation as a foundation for understanding the mechanisms of edema formation in specific disease states, as well as the implications for treatment. Specific etiologies are reviewed to compare the diseases that manifest this common physical sign. Finally, we review the clinical approach to diagnosis and treatment strategies.