Introduction. Osteitis condensans ilii (OCI) is a condition characterized by benign sclerosis of the iliac bone in the portion adjacent to the sacroiliac joints, which is radiologically manifested by triangular opacities at the level of this portion. Among the clinical manifestations, localized low back or lumbosacral pain is often attested, which is found in the gestational or post-partum period. The pain may worsen during physical exertion or during menstruation and may be accompanied by myalgia. Material and methods. The epidemiological, clinical and paraclinical data were used to highlight this study, followed by the conclusions of multidisciplinary specialists, retrieved from the inpatient medical records of 3 women with OCI, who were admitted for diagnosis and treatment. Results. 3 cases of imaging-determined OCI will be presented, which were initially diagnosed with seronegative spondyloarthritis (SpA). Through them, we would determine the varieties between the OIC forms and their differential diagnosis with SpA. The results of the lab tests do not reveal specific changes, so the markers of inflammation (C-reactive protein, erythrocyte sedimentation rate) were normal. Also, unlike SpA, the marker HLA-B27 is in most cases negativ  Conclusions. According to the results of the presented clinical cases, OCI is often confused with sacroiliitis, which leads to misdiagnosing and erroneous treatment tactics. Thus, in order to establish a true diagnosis, it is necessary to collect a detailed history, perform a comprehensive objective examination, which includes the character of the pain and its triggers, the lack of inflammatory lab markers and the radiological presence of the sclerosis areas at the level of the iliac bone, not involving the sacroiliac joints.