A retrospective review of 304 consecutive microvascular free flaps to the lower extremity was done to identify the patterns of usage, results, and problems. The most common indication (91%) was for the replacement of extensive tissue loss caused by motor-vehicle injuries. Most of the defects were below the mid-tibia (73%). The associated compound fractures were predominantly gradable as Gustilo type Illb. The latissimus dorsi, the rectus abdominus, and the scapular skin were the flaps used most commonly for coverage (77%). The overall flap failure rate was 8%, compared with 3% for our series of non-lower extremity cases, and 0% for the non-traumatic lower extremity cases. The magnitude of the traumatic insult was the most significant factor associated with anastomotic failure. The rate of anastomotic thrombosis doubled in the presence of vascular trauma, increased threefold in the presence of larger bony defects, and increased fivefold when vein grafts were needed. Experience was important in reducing the complications and improving the results. Fourteen patients (6%) underwent an amputation within the first 3 months, ten of them because of flap failure. Of 85 patients followed up for over one year, 91% had recovered good to excellent leg function. The ability to add healthy and well vascularized tissue to the traumatized limb is critical for the achievement of: 1) early definitive wound healing and restoration of function; 2) salvage of many impending amputations; 3) better prosthetic stump reconstructions; 4) better esthetic results.