In 1973, Daniel and Taylor reported the first successful microsurgical transplantation of the groin flap as a one-stage reconstrutive procedure. The free vascularized groin flap has several advantages, such as its potenitally large size, comfortable position of the patient during operation, minimal donor site morbidity, possible coverage of the donor site scar with a bikini, its multiple arterial and venous system, and the potential for incorporating bone with the overlying skin. The authors perfomed free groin flaps in 36 patients at Severance Hospital, Yonsei University College of Medicine from January 1985 to August 1988. The results were as follows : 1. Good results were obtained in 26 of 36 cases with a 72.2% success rate. The results were better in the upper extremity than the lower extremity. 2. The anatomical classification of the superficial circumflex iliac artery was as follows : a common origin of the superficial circumflex iliac artery and the superficial inferior epigastric artery in 39.5% of cases, an absent superficial inferior epigastric artery with a large compensatory superficial circumflex iliac artery in 36.8%, separate origins of the two vessels in 7.9%, and an origin from a profunda femoral artery in 15.8%. This result was similar to that of Daniel and Taylor. 3. The average diameter of the artery was 1.0mm and the average length of the vascular pedicle was 9.0mm. 4. The results were better in the end to side anastomosis than the end to end anastomosis, but there was no statistical significance. 5. In the 10 failed cases, free scapular flaps were performed in 4 cases, skin grafts in 5 cases, and the cross leg flap in one case. 6. The donor sites healed well by primary closure without functional disturbance except in one cases in which secondary closure was done. In conclusion, the free vascularized groin flap can be used without restriction as a onestage reconstruction of an extensive soft tissue injury of the extremity.