Viscosupplementation by injection of hyaluronic acid into the ankle can be used to provide pain relief and to delay the need for surgery in patients with osteoarthritis of the ankle. In the present investigation, we prospectively evaluated 50 consecutive patients (25 males and 25 females) undergoing a 3-injection protocol of sodium hyaluronate viscosupplementation in the ankle from January 2014 to January 2015. The Foot and Ankle Outcomes Score was used to compare the patients’ pre- and post-treatment opinions about their ankle problems. The mean pretreatment Foot and Ankle Outcomes Score was 48 ± 6.3 (range 25 to 84) and the 6-month post-treatment score was 78 ± 5.8 (range 48 to 100). This difference was statistically significant (p = .003). From our findings in the present prospective cohort study, we have concluded that intra-articular injection of sodium hyaluronate viscosupplementation is a useful conservative therapy for osteoarthritis of the ankle.