Sacral stress fractures are an unusual but curable cause of low-back pain that should be considered in differential diagnosis, particularly in elderly osteoporotic patients. Rarely, they may occur in young women during the last trimester of pregnancy or a few weeks after delivery. Encompassing fatigue and insufficiency fractures, the occurrence of sacral stress fractures appears to be relatively under-reported, because of the general lack of awareness of this condition and the non-specificity of symptoms. Plain radiographs of the pelvis are the first exam performed but they are often inconclusive, whereas MRI and CT scans are the examinations of choice to establish the diagnosis. The purpose of this review is to increase awareness of this condition so that clinicians may consider sacral stress fracture in the differential diagnosis of low-back and pelvic pain, particularly in elderly patients without a history of trauma.