what is the longest vein
Hywel Vaughan. answered on 25 Jun 2010: Hi wildrosa, The biggest vein in the body is the âinferior vena cavaâ â this is the vein that returns the blood from the bottom of your body to your heart. The blood is de-oxygenated, and enters the right atrium of your heart â this is at the lower right, back side of your heart.