From the Cincinnati Sportsmedicine and Orthopaedic Center and The Deaconess Hospital, Cincinnati, OH. Research Funded by the Cincinnati Sportsmedicine Research and Education Foundation and the United States Olympic Committee. The purpose of this study was to develop a physiological profile of the elite soccer athlete. Protocols were developed to assess flexibility, knee ligament translation, body composition, anaerobic power, lower extremity functional performance, and muscle strength. Eighty-three male U.S. National Team players provided data for this study. Different protocols were used over the years the data was gathered. Each area was tested, using a subset of the total group. The physiological profile of the elite soccer player was compiled from results in each area tested. The players were flexible, on the whole, although 17% of the players demonstrated hamstring tightness. All but one player tested had less than 2.5 mm anterior/posterior (A/P) knee ligament translation. The average body fat was 9.5%, and all athletes performed normally on the function tests. The mean power output on Wingate testing was 8.1 Watts per kilogram body weight. The average hamstring-to-quadricep torque ratio (H/Q) at 60 degrees /sec was 56% (right) and 56.6% (left), and at 450 degrees /sec, was 67.1% and 70.1 %. Identification and measurement of these key physiological qualities for the elite soccer athlete will provide standards and a baseline for trainers, coaches, players, and future investigators. J Orthop Sports Phys Ther 1990;12(4):147-152.