Introduction: The aim of our study was to evaluate ankle involvement in adult polyarticular juvenile idiopathic arthritis (JIA) by clinical, radiographic and ultrasound examination. Methods: Cross-sectional study of patients with polyarticular JIA over an 18-month period. Results: Our population comprised 4 men and 25 women, with a mean age of 42.1±12.5 years. Among patients with talocrural involvement (n=23), ankle X-rays and ultrasonography revealed talocrural involvement in 55% and 72% of cases respectively. BMI was significantly associated with the occurrence of talocrural involvement (p=0.03), and patients with ankle involvement had significantly higher CRP levels than the group without ankle involvement (p=0.02). Talocrural involvement was significantly associated with knee involvement (p=0.01).Conclusion: Ultrasonographic involvement of the talocrural joint was frequent in our study (72%). Ankle involvement was associated with BMI, high CRP and knee involvement.