Most patients with low back pain experience loss of spinal and hip extension range of motion. The limitation appears to involve significant iliopsoas myofascial dysfunction manifested in tenderness, as shown by deep abdominal palpation of the psoas muscle, hip flexor contracture, pain elicited by the stretch maneuver of the spine and hip, and relative weakness of the psoas muscle when tested manually. These signs assisted in identifying the source of low back pain in six patients who had failed to respond to prior treatment. Therapy consisted of iliopsoas trigger point treatment using a dry needling technique, followed by self-administered postisometric relaxation exercise of the iliopsoas. In all cases, marked improvement of hip and spine extension, dramatic reduction of pain, and return to normal activity resulted. Given the low risk-to-benefit ratio, trigger point treatment is indicated in "failed back syndrome" and chronic low back pain after conservative therapy or surgery have been tried without success.