Background: Chronic low back pain (CLBP) is a leading cause of pain globally and axial spondyloarthritis (AxSpA) is an important cause. Lumbar magnetic resonance imaging (MRI) is frequently used to diagnose CLBP. Aim of the work: To determine the added value of coronal lumbosacral T2-weighted Short Tau Inversion Recovery (T2-STIR) sequence with routine lumbar MRI in detecting sacroiliitis in patients with CLBP in order to enable early referral for the diagnosis of AxSpA, and to evaluate the influence of age and gender. Patients and methods: The lumbar MRI of 1000 patients aged 18-65 years with CLBP presenting to the Physical Medicine and Rehabilitation (PMR) outpatient clinics of Selcuk University, and following up for at least three months and have a lumbar MRI, were retrospectively evaluated, and the presence of active sacroiliitis in the coronal T2-STIR sequence was investigated by two experienced radiologists guided by the Assessment of SpondyloArthritis International Society (ASAS) criteria. Results: The mean age of patients was 42.2±12.8 years. 691 (69.1%) were females and 309 (30.9%) males (F:M 2.2:1). Of all participants, 11.3% had active sacroiliitis and and 11.7% had non-specific bone marrow edema (BME). Active sacroiliitis was seen in 72 (13.1%) patients aged ≤45 and 41 (9.1%) aged >45 (p=0.046). 91 female (13.2%) and 22 males (7.1%) had active sacroiliitis (p=0.005). Conclusion: In this study, radiographic active sacroiliitis was detected on lumbosacral coronal T2-STIR sequences in chronic low back pain patients, particularly in women and those aged ≤45 years. Further clinical evaluation and prospective studies are required to confirm the potential usefulness in earlier diagnosis or referral.