Sudden low back pain is common in elderly women. It causes physical and mental stress, and results in deterioration of functional movement and in activities of daily living. Awareness of possible sacral insufficiency fracture is important; they may be demonstrated by imaging modalities, mainly radionuclide bone scan. Prognosis is good and accurate diagnosis serves to exclude malignancy and relieve fear of chronic pain and disability. We describe 4 women, aged 84, 82, 71 and 77 who illustrating the clinical and imaging findings of this disorder.