Self-reported studies have demonstrated efficacy of hyaluronic acid (HA) therapy. Gait analysis may objectively demonstrate changes associated with HA therapy. Fifty-three consecutive patients with unilateral osteoarthritis (OA) of the knee were evaluated with a validated and sensitive gait laboratory previously used for gonarthrosis. Two 100-meter walks were performed before and after HA therapy. Nineteen parameters were measured. In addition, the subjective response to treatment was correlated with changes in gait parameters. Single-limb support time, velocity, fatigability, and swing phase were not improved. Only double-limb support time was found to be significantly different (P = .04). The remaining gait variables were not changed. Separately, the subset of patients that achieved greater than 70% subjective pain relief had no objective improvements in gait parameters. Hyaluronic acid therapy may result in a placebo effect for the treatment of gonarthrosis.