Leg swelling is an extremely frequent symptom with a broad variety of largely differing causes. The most important mechanisms behind the symptom include venous and lymphatic pathology, volume overload, increased capillary permeability, and lowered oncotic pressure. Therefore, the most frequent diseases associated with leg swelling are deep vein thrombosis and chronic venous insufficiency, primary or secondary lymphedema, cardiac failure, hypoproteinemia due to liver or renal failure, idiopathic cyclic edema, and drug-induced edema. Lipedema as a misnomer represents an important differential diagnosis. History and physical examination, when based on a sound knowledge of the diseases of interest, enable a conclusive diagnosis in most cases. Additional test are required in only a minority of patients. The present review discusses pathophysiology and clinical features of the most prevalent types of leg swelling. Finally, a brief guide to differential diagnosis is given.