Growing interest in complementary and alternative medicine in the United States has been paralleled by increased use of spinal manipulative therapy in an attempt to manage symptoms of low back pain, spinal stenosis, and spondylolisthesis. Chiropractors have been the main practitioners of spinal manipulative therapy, with osteopaths and physical therapists providing a smaller fraction of these services. Theories explaining the mode of action of spinal manipulative therapy are largely preliminary and have focused on the mechanical effects of manipulative forces on the spine and neurologic responses to manipulation. The effects of spinal manipulation on patients with both acute and chronic low back pain have been investigated in randomized clinical trials. Most reviews of these trials indicate that spinal manipulative therapy provides some short-term benefit to patients, especially with acute low back pain.