Polytrauma includes simultaneous injuries to two or more regions of the body, which almost always represent a life-threatening condition. It is the most common cause of death in people between five and forty-five years of age and one of the leading causes of death in the world. Most of the deaths during polytrauma occur within 24 hours of the injury, and one of the most common causes is massive bleeding. Massive bleeding is a medical term describing the loss of the entire blood volume within 24 hours with the consequent development of hypovolemic shock. The loss of large amounts of blood in combination with the characteristics and severity of the injuries causes a strong inflammatory response. The resulting multiple hormonal, immune and metabolic changes often cause irreversible organ damage and a poor treatment outcome. Hypovolemic shock is responsible for 40% of deaths associated with injuries in polytrauma. Early recognition of massive bleeding and timely and correct volume replacement is the best opportunity to reduce the overall mortality of polytraumatized patients. This paper summarizes the basic features of polytrauma and massive bleeding and presents modern knowledge about how to manage them. In the second part it presents a case report of acute massive bleeding during polytrauma.