ABS TRACT Insufficiency fractures occur when normal stress is applied to bone with low mineralization and elastic resistance. Postmenopausal osteoporosis, pregnancy, postpartum period, and sports activities can result in insufficiency fractures. Clinical suspicion is important in sacral insufficiency fractures. Computed tomography, scintigraphy, and magnetic resonance imaging are used in undiagnosed cases. Bed rest, analgesics, anti-inflammatory drugs, and physical therapy modalities can be used for pain control. Sacral insufficiency fracture should be kept in mind in elderly osteoporotic patients with low back and/or hip pain unresponsive to treatment. In this case report, we will present a 77-year-old patient with overlooked sacral insufficiency fracture. The patient, who had persistent low back and hip pain for three months, was misdiagnosed as sacroiliitis.