Varicose veins, also known as varicoses, are a medical condition in which superficial veins become enlarged and twisted. These veins typically develop in the legs, just under the skin. Varicose veins usually cause few symptoms. However, some individuals may experience fatigue or pain in the area. Complications can include bleeding or superficial thrombophlebitis. Varices in the scrotum are known as a varicocele, while those around the anus are known as hemorrhoids. Due to the various physical, social, and psychological effects of varicose veins, they can negatively affect one's quality of life.

Varicose veins have no specific cause. Risk factors include obesity, lack of exercise, leg trauma, and family history of the condition. They also develop more commonly during pregnancy. Occasionally they result from chronic venous insufficiency. Underlying causes include weak or damaged valves in the veins. They are typically diagnosed by examination, including observation by ultrasound.

By contrast, spider veins affect the capillaries and are smaller.

Treatment may involve lifestyle changes or medical procedures with the goal of improving symptoms and appearance. Lifestyle changes may include wearing compression stockings, exercising, elevating the legs, and weight loss. Possible medical procedures include sclerotherapy, laser surgery, and vein stripping. Reoccurrence is common following treatment.

Varicose veins are very common, affecting about 30% of people at some time in their lives. They become more common with age. Women develop varicose veins about twice as often as men. Varicose veins have been described throughout history and have been treated with surgery since at least A.D. 400.