Patients with chronic pain frequently have serious psychiatric disturbances - most often, clinical depression. Depression should not be discounted or ignored because of its association with chronic pain. Not all patients with chronic pain have clinical depression, but when depression is present, it influences the pain and may, in turn, be influenced by the level of pain. It is essential to try to maximally treat the clinical depression, if present; to reduce or resolve the chronic pain; or at least to prepare the patient to be an optimal candidate when structural disease indicates surgical intervention. Just as there are evolving treatment algorithms for low back pain, there are also established algorithms for the treatment of clinical depression, with or without the association of back pain or other medical illness. A clinician who is treating back pain should be familiar with a brief, easily administered instrument to screen for depression, such as the Beck Depression Inventory, and should be prepared to work with a mental health professional to treat the more distressed patients. Both the pain and the depression must be treated to achieve an optimal outcome.