Low back pain is a common complaint in primary care practice, particularly among older patients. The office-based workup starts with a careful history aimed at determining the onset, location, and severity of pain. A physical examination includes attention to gait, palpation, and some simple neurologic tests. Most patients require plain x-rays. Bone scans are useful for identifying suspected tumors and infections; CT and MRI are indicated in specific cases. Although the origin of most low back pain is indeterminate, the workup may uncover some important causes in older adults, including lumbar spinal stenosis, osteoporotic vertebral fractures, and metastatic disease to the spine.