Leg injuries in real-world crashes have been studied in order to examine the effects of design and regulation on leg injury outcome. Data from the UK Co-operative Crash Injury Study have been used in this study. Lower extremity injuries are by far the most costly injuries and account for some 43% of injury costs in both front and struck-side crashes. In terms of injury frequency, pelvis and lower extremity injuries account for 25.8% of AIS2+ injuries in frontal crashes in `newer' vehicles (those manufactured post-1998) and 20.7% of pelvis and lower extremity injuries in struck-side crashes in newer vehicles. In terms of injury type, tibia and fibula fractures appear to have decreased dramatically in frontal crashes but femur and foot/ankle injuries have not decreased by the same extent. Examination of passenger car performance in frontal crashes shows some correlation with EuroNCAP test score for lower extremity injury risk in real-world crashes. A number of case studies have been used to highlight some of the findings in the study including the long-term consequences of lower extremity injury on quality of life.