The aim of this study is to examine the flexibility of the structures around the ankle in individuals with unilateral chronic ankle instability. Individuals between the ages of 18-45 who have been diagnosed with chronic ankle instability by an orthopedist and who have unilateral instability will be included in the study. The flexibility of the healthy and instability sides will be evaluated. Demographic information of the individuals will be recorded and clinical evaluations will be made. The severity of ankle instability will be evaluated with the Functional Ankle Identification (FABIT). The foot posture of the individuals participating in the study will be evaluated with the Foot Posture Index, and the degree of flat feet will be evaluated with the Navicular Drop Test. The flexibility of the gastrocnemius, tibialis anterior, peroneus longus, achilles tendon and plantar fascia of the individuals participating in the study will be measured with a myotonometer.