Sacroilitis is discomfort arising from the SI joint. The sacroiliac (SI) joint is formed by the junction of the sacrum, a flat triangle shaped bone between the two iliac bones that comprise part of the pelvis. SI joint pain can result in low-back, hip and leg pain. Sacroilitis may be triggered by various types of arthritis, trauma, skeletal imbalances or also by certain autoimmune diseases that are associated with inflammatory arthritis for example ankylosing spondylitis, psoriatic arthritis and many others. Other potential triggers are pregnancy, lumbar fusion surgery, infection, insufficiency fractures of sacrum or tumors. SI joint discomfort is very common and can be easily diagnosed and treated with a simple injection. Accurate diagnosis requires anesthetizing the target joint and determining if the patient has concordant relief of pain. SI joint dysfunction is easily treatable.