Rheumatic diseases have not proved to be more prevalent among neurologic or psychiatric patients than in the general population, except for osteoarthritis in some chronic disabling neurologic conditions (poliomyelitis, spinal cord injury). Some neurologic entities with relevant musculoskeletal manifestations are described here. The lower prevalence of rheumatoid arthritis in schizophrenia patients is mentioned, and a brief description is presented of somatoform disorders that may confound diagnosis with rheumatic diseases. Factitious disorders and malingering are frequently presented with rheumatic complaints such as low back pain and may have an important impact on the costs associated with the disease. Finally, some of the immune system abnormalities described in major depression and schizophrenia are mentioned with a clear reference to the growing field of psychoneuroimmunology. This paper will not address the issue of neurologic or psychiatric manifestations of rheumatic diseases.