A series of 489 consecutive patients with definite or classical rheumatoid arthritis was followed for a mean of 11.2 years. Cohort-analysis of the series showed a three-fold increase in mortality overall in comparison with age- and sex-specific rates in the general population. In patients first seen in hospital early in the course of the disease (less than 5 years from onset), the excess of deaths from circulatory, respiratory and musculoskeletal disorders was highly significant. Malignant disease and digestive system disorders accounted for a small excess of borderline significance. Patients who were referred later (greater than 5 years from onset) experienced, in addition, a highly significant excess of deaths from infections and disorders of the digestive and genito-urinary system but not from malignant neoplasms.