Abstract Objective: To examine the acute effects of aquatic and land treadmill exercise on gait kinematics as well as the level of disease-specific and movement-related pain for individuals with osteoarthritis. Design: Quasi-experimental crossover design. Setting: Biomechanics laboratory. Participants: Participants (NZ14; age, 43e64y) diagnosed with osteoarthritis at the knee (nZ12), osteoarthritis at the knee and ankle (nZ1), or osteoarthritis at the knee and hip (nZ1). Interventions: Participants performed 3 exercise sessions separated by at least 24 hours in 1 week for each mode of exercise (aquatic treadmill and land treadmill). Main Outcome Measures: Gait kinematics and pain were measured before and after each intervention. Results: The angular velocity gain score during stance for left knee extension was improved by 38% after aquatic treadmill exercise (PZ.004). Similarly, during swing, the gain scores for angular velocity were also greater for left knee internal rotation and extension by 65% an