The Minnesota Multiphasic Personality Inventory (MMPI) is widely used in the psychological assessment of patients with chronic low back pain (LBP). Patients' profiles have been used in a number of ways: in attempts to discriminate between cases; as predictors of both medical treatment and pain management program outcomes; and in attempts to assess degree of disability. Studies reviewed here indicate that the concept of psychological etiology of chronic LBP, despite widespread use, has failed to differentiate patients and to reliably predict response to specific treatment. A promising alternative approach has emerged in recent years: profile distinctions between different types of psychological response to chronic LBP. These subgroups are associated with different pain-related behaviors and may show differential response to various treatments, although further work remains to be done to specify the relationships more precisely. Methodological difficulties that continue to appear in the literature are addressed and recommendations for further developments in the use of the MMPI with this patient population are made.