Background: We sought to determine whether symptomatic medial knee osteoarthritis is associated with aberrant loading across the foot during gait. Methods: Twenty-five individuals with medial knee osteoarthritis were compared with 25 controls. Knee radiographs and Western Ontario and McMaster Universities Arthritis Index questionnaires were obtained. Participants walked barefoot over pressure sensors, and the center-of-pressure trace was plotted against the axis of the foot, and a center-of-pressure index was calculated. Results: The center-of-pressure indices in the medial knee osteoarthritis group demonstrated high lateral loading compared with the central center-of-pressure pattern in controls ( P < .001). There was a correlation between the severity of pain and the center-of-pressure index in patients with medial knee osteoarthritis but no correlation between center of pressure and radiographic severity. Conclusions: The plantar pressure patterns of patients with medial knee osteoarthritis demonstrated greater loading of the lateral aspect of the foot during the contact and midstance phases of gait but not during propulsion compared with those of controls, suggesting that loading patterns in the feet are related to osteoarthritis in the knee. (J Am Podiatr Med Assoc 100(3): 178–184, 2010)