Study of more than 1,000 cases of rheumatoid spondylitis encountered at the Mayo Clinic has yielded data which may help to clarify certain aspects of this disease and may help the physician to answer a few of the questions frequently asked concerning the condition. These questions are as follows: What is the incidence of this disease in [male] [male] as compared to [female] [female] ? What is the age at onset in this disease ? What is the location of initial symptoms of rheumatoid spondylitis? What is the course of the symptoms in rheumatoid spondylitis? What is the predictable duration of the disease? What is the possibility of the disease being limited to spinal involvement ? What is the incidence of arthritis in special regions during the course of rheumatoid spondylitis? The erythrocyte sedimentation rate and the roentgenographic findings in cases of rheumatoid spondylitis are discussed briefly.