PURPOSE: Decreased hip strength has been theorized to contribute to the development of patellofemoral pain. The purpose of this study was to test for strength differences of six hip muscle groups in collegiate female athletes diagnosed with unilateral patellofemoral pain compared with the unaffected leg and noninjured sport-matched controls. METHODS: At four Division III schools, all collegiate female athletes experiencing unilateral patellofemoral pain were recruited during the 2004-2005 academic school year. The athletes were diagnosed with patellofemoral pain by sports medicine-trained family physicians or orthopedic surgeons. Hip strength of six different muscle groups was tested using a handheld dynamometer. The highest value of two trials was used, and strength values were normalized to body weight. The measurements from the injured leg were compared with the uninvolved leg and also with uninjured control subjects matched for sport. RESULTS: Thirteen athletes were diagnosed with unilateral patellofemoral pain. The injured-side hip abductor (P = 0.003) and external rotator muscle groups (P = 0.049) were significantly weaker than the noninjured sides. There were no significant differences in the other hip muscles tested. In addition, the injured legs were significantly weaker in five of the six hip muscle groups compared with the control group. CONCLUSIONS: The results of this study show that hip abductors and external rotators were significantly weaker between the injured and unaffected legs of the injured athletes. In addition, injured collegiate female athletes exhibited global hip weakness compared with age- and sport-matched asymptomatic controls. Screening for hip muscle weakness and adding strengthening exercises to the affected hip muscles may be important factors in managing female athletes with patellofemoral pain.