Study Design: One group pretest-posttest exploratory design. Objectives: Primary purposes of this study were to examine the short-term effect of hip mobilizations on pain and range of motion (ROM) measurements in patients with knee osteoarthritis (OA) and to determine the prevalence of painful hip and squat test findings in both patients with knee OA and asymptomatic subjects. The secondary purposes were to assess intrarater reliability and to determine whether fewer subjects experienced painful test findings following hip mobilization. Background: Conservative intervention, including manual physical therapy applied to the lower extremity, has been shown to reduce impairments associated with knee OA. Methods and Measures: One rater pair administered 4 clinical hip tests to 22 patients with knee OA (mean age, 61.2 years; SD, 6.1 years) and 17 subjects without lower extremity symptoms or known pathology (mean age, 64.0 years; SD, 7.9 years). Therapy, 3151 Scott Road, Room 1303, Fort Sam Houston, TX 78234. E-mail: Robert.Wainner@cen. amedd.army.mil Conclusions: Patients experienced increases in ROM, decreased pain, and fewer subjects had painful test findings immediately following a single session of hip mobilizations. Examination and intervention of the hip may be indicated in patients with knee OA. J Orthop Sports Phys Ther 2004;34:676-685.