Objective.The aim of this study was to evaluate the influence of sex on response to treatment and disease remission in patients with axial spondyloarthritis (axSpA).Methods.In this retrospective multicenter study, patients with axSpA, according to the Assessment of Spondyloarthritis international Society (ASAS) criteria for axSpA, and treated with adalimumab, etanercept, golimumab, or infliximab, were studied. We compared clinical characteristics, patient-reported outcomes, disease activity, function, and response to treatment in male and female patients with this disease.Results.Three hundred forty patients with axSpA (270 with ankylosing spondylitis, 19 with psoriatic arthritis with axial involvement, and 51 with nonradiographic axSpA) were studied. Male subjects had a significantly higher prevalence of grade IV sacroiliitis, higher levels of serum C-reactive protein, lower Maastricht Ankylosing Spondylitis Enthesitis Score, and fatigue when compared with females. Further, Kaplan-Meier survival curves showed that the rate of partial remission, ASAS40 response, and Ankylosing Spondylitis Disease Activity Score (ASDAS) major improvement, but not ASDAS inactive disease, were significantly lower in female patients.Conclusion.Our data suggest that female sex was associated with a lower rate of response to treatment and of disease remission in patients with axSpA treated with antitumor necrosis factor-α drugs.