Sacroiliac joint related pain has a prevalence of 16% to 30% among chronic low back pain patients. The sacroiliac joint is a large load bearing joint and a common pain generator in patients with chronic low back pain. The joint is innervated by a complex web of sensory nerves and, thus, presenting pain patterns are often variable and shared by other concurrent pathologies. Diagnosis of sacroiliac joint dysfunction can become overshadowed by more obvious diagnoses such as lumbar radiculopathy. Unless a clinician actively rules out sacroiliac joint pain, it can easily be missed and forgotten during the workup for back pain. This presentation will review the anatomy and physiology of the sacroiliac joint. To be discussed: sacroiliac joint biomechanics, dysfunction, and pathophysiology of chronic sacroiliac joint pain. The diagnosis and treatment, including current controversies in sacroiliac joint fusion will be reviewed. The topics introduced will help both interventional and noninterventional pain physicians understand sacroiliac joint dysfunction as a commonly overlooked chronic low back pain generator.