OBJECTIVES: There is growing interest in the role of the knee adduction moment in the pathogenesis of knee pain and osteoarthritis. It is unclear whether the knee adduction moment is similar between the dominant and nondominant legs during locomotion. This study examined whether asymmetry exists in the peak knee adductor moments during gait in healthy adults. DESIGN: Cross-sectional study. SETTING: Musculoskeletal Research Centre, La Trobe University, Melbourne, Victoria, Australia. PARTICIPANTS: Three-dimensional Vicon gait analyses were performed for 17 healthy men and women. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The external dominant and nondominant peak knee adduction moments during early and late stance were analyzed to determine whether any significant differences occurred between limbs. RESULTS: Peak knee adductor moments for dominant and nondominant limbs were significantly correlated during early (R=0.61, P=0.009) and late (R=0.72, P=0.001) stance. After adjustment for age and sex, there was an associated 0.58 (P=0.030) and 0.98 (P=0.009) unit increase in the peak knee adduction moment in the nondominant leg, for every 1 unit increase in the dominant leg during the early and late stance phases of gait, respectively. Further evidence for symmetry was provided by the symmetry index, which was 0.04% and 0.62% for early and late stance, respectively. CONCLUSIONS: In healthy subjects, the magnitude of the dominant limb peak external knee adduction moments during stance, and in particular late stance, appears representative of the magnitude of the moment in the nondominant limb. These findings imply symmetry between these moments and may have important implications when collecting data for limb analyses among healthy subjects. Whether gait symmetry protects against the onset of unilateral (or increases the risk for bilateral) pathological joint changes will need to be confirmed longitudinally.