Physical activity is recommended in axial spondyloarthritis (axSpA) but may be insufficiently performed. The objective of this study was to assess physical activity in axial spondyloarthritis and to explore its explanatory factors. This was a cross-sectional study of patients with definite axSpA. The level of physical activity (International Physical Activity Questionnaire-Long form, IPAQ-L), type of aerobic exercise and the Exercise Benefits and Barriers Score were collected. Multivariate logistic regression analyses were performed to explain levels of exercise at least as recommended by the World Health Organization. In all, 203 patients were included: mean age 46.0 +/- A 11.6 years, 108 (53.2 %) males, mean Bath Ankylosing Spondylitis Activity Index (0-100) 37.8 +/- A 19.9; 137 (68.8 %) were treated with TNF-inhibitors. In all, 111 patients (54.7 %) were exercising at least as recommended; 96 (47.2 %) were in the 'high physical activity' category. Aerobic exercise >30 min was performed at least once a week by 61 (30.0 %) patients; the most frequent activities were energetic walking (31.0 %) and swimming (21.2 %). Main perceived benefits of exercising were improving physical fitness and functioning of the cardiovascular system, and the main barrier was physical exertion. Patients with paid employment had lower levels of physical activity whereas other demographic variables, disease activity/severity or TNF-inhibitor treatment were not predictive. One half of these patients performed enough physical activity according to the recommendations, similarly to the French population. Levels of physical activity did not appear to be explained by disease-related variables. Physical activity should be encouraged in axSpA.