Objective: to evaluate the effect of golimumab (GLM) on the clinical, functional, and instrumental manifestations of coxitis in ankylosing spondylitis (AS).Subjects and methods. The non-interventional prospective multicenter cohort study GO-COX conducted in the medical centers of the Russian Federation enrolled 39 patients with AS (meeting the modified New York criteria) and coxitis with BASRI-hip score 0–2, who were prescribed GLM as the first biologic agent at a dose of 50 mg per month. The patient's health status was assessed using the Bath Ankylosing Spondylitis Functional Index (BASFI), the Bath Ankylosing Spondylitis Metrology Index (BASMI), the Ankylosing Spondylitis Disease Activity Score-C-Reactive Protein (ASDAS-CRP), and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) before and at 6 and 12 months after GLM treatment initiation. Based on the data of radiographs (the Bath Ankylosing Spondylitis Radiology Hip Index (BASRI-hip) scoring system), ultrasonography (USG), and STIR and T1 magnetic resonance imaging (MRI), the investigators assessed the manifestations of coxitis. The planned follow-up duration was 2 years. This paper includes 12-month follow-up results in 22 patients.Results and discussion. At 12 weeks of GLM therapy, there were significant positive index changes: a decrease in BASDAI by an average of 3.28±1.62, in ASDAS-CRP by 2.20±0.95, in BASFI by 2.52±2.09, and in BASMI by 1.41±1.50 (p<0.0001). One year after GLM therapy initiation, the BASRI-hip values remained unchanged; 40 to 60% of patients had no MRI and USG signs of coxitis.Conclusion. At 12 weeks, GLM therapy in patients with AS and coxitis provided a reduction in the clinical and instrumental signs of coxitis, as evidenced by MRI and USG (a significant decline in the proportion of patients with subchondral bone edema and intraarticular effusion), and also effectively suppressed other manifestations of inflammatory activity.