Objective: The purpose of this study was to investigate whether the intrinsic foot muscle training method can improve the medial longitudinal arch in patients with chronic ankle injury and with pronated feet, as well as to investigate for the most effective exercise method for these patients. Design: Randomized controlled trial. Methods: Thirty men and women with pronated feet had participated in this study and were allocated to either the short foot exercise group (SFEG) or the towel curl exercise group (TCEG) randomly. SFEG and TCEG underwent exercises three times a week for 8 weeks, with three sets per day, totalling up to 5 minutes per day. The navicular drop test (NDT) was used in order to assess for changes in the medial longitudinal arch and the Cumberland ankle instability tool (CAIT) was used to assess for ankle instability of the chronic ankle sprain patients. Results: There was a significant increase in CAIT scores in the SFEG (p<0.05) and a significant difference between groups was presented (p<0.05). The NDT scores were significantly decreased in both groups (p<0.05). In the SFEG, the NDT scores were more decreased than in the TCEG (p<0.05). Conclusions: These results suggest that short foot exercises are more effective in providing intrinsic foot muscle training for patients with pronated feet among chronic ankle sprain patients. Furthermore, short foot exercises may be used to provide ankle stability.