Over the last few decades, there have been many important advances in the treatment of severe lower limb injuries. This article looks at a few of the more widely used classification systems and Injury Severity Scores to examine their utility in a practical setting. Gustilo and Anderson formulated their landmark classification system in 1976 (J Bone Joint Surg Am. 1976;58:453-458). For the Gustilo classification system to serve any useful purpose, it is necessary to include supplemental information, whenever discussing these injuries, that includes the mechanism and energy of the injury and the presence of any other concomitant injuries or comorbidities. Byrd et al (Plast Reconstr Surg. 1985;76:719-728) recognized some of the shortcomings of the Gustilo-Anderson system and proposed a classification system of their own in 1985. The Byrd-Spicer classification is less commonly used, mainly because of a large degree of interobserver variability, but it includes energy and presence of devitalized tissue. The Predictive Salvage Index, devised in 1987, recognized the importance of vascular injury as a prognostic indicator and was formulated in an attempt to avoid not only unnecessary amputations, but also to avoid protracted attempts at salvage that might eventually be converted into a delayed amputation. The Mangled Extremity Severity Score looked at 4 variables: patient age; the presence and duration of shock; ischemia time; and the energy of the injury. Critics question the relevance of its parameters. The 7 components of the Limb Salvage Index include injury to an artery, deep vein, nerve, bone, skin, and muscle as well as warm ischemia time. However, predictive results have not been reproduced. The Hanover Fracture Scale was initially developed on the basis of 13 weighted variables to quantify risk factors for amputation and complications in high-energy trauma to a limb. This included index bacteriology, and was weighted heavily toward the presence of vascular injury. Nerve Injury, Ischemia, Soft-Tissue Injury, Skeletal Injury, Shock, and Age of Patient Score attempted to address criticized weaknesses of the Mangled Extremity Severity Score. These scores can be useful tools in the decision-making process when used cautiously, but should not be used as the principal means for reaching difficult decisions.