BACKGROUND: Symptomatic accessory navicular syndrome (ANS) typically develops in young athletes. The symptoms are exacerbated during exercise or while walking, affecting the sports performance of athletes. The purpose of this study was to evaluate the radiologic findings and clinical course in athletes with accessory navicular syndrome (ANS) in comparison with a nonathletic population. METHODS: Seventy-nine patients with ANS between August 2012 and August 2013 were included. Overall, 29 were athletes and 50 were not athletes, and 19 (2 athletes and 17 nonathletes) of them improved after at least 6 months of conservative treatment. The records of 60 patients (64 consecutive feet) of ANS treated by modified Kidner operation were evaluated retrospectively. The study population included 27 athletes (31 feet) and 33 nonathletes (33 feet). Clinical features and radiologic findings were compared between them. RESULTS: Overall, 34% of the nonathletes improved after conservative treatment, but only 6.9% of athletes improved (P < .001). Mean age at surgery in the athlete group was 16.1 years (range, 12-26), and 24.3 years (range, 12-52) in the nonathlete group (P < .001). There was a history of trauma in 23 feet (74%) of the athlete group and in 13 feet (39%) of the nonathlete group (P = .006). Eighteen feet (58%) in the athlete group and 11 feet (32%) in the nonathlete group showed movement between the 2 bones (P = .047). Bone marrow edema was observed in both navicular and accessory navicular in all of the athletes (27/27, 100%). But it was only present in 80% (16/20) for nonathletes (P = .012). CONCLUSION: The radiologic findings and clinical course of athletes were different from that of the general population. Their symptoms were more refractory to conservative treatment than the nonathletes group. Therefore, early operative treatment could be considered in cases of symptomatic ANS especially for athletes. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.