This study of rheumatoid arthritis has been made in Jondal, Norway, on 803 persons between the ages of 16 and 75 years. Patients suspected of suffering from joint disease other than traumatic lesions were selected from the general practitioner's file, and further information on these patients was obtained from the local hospital and from personal interviews. It was found that 0.5% of the men and 1.2% of the women suffered from rheumatoid arthritis. Six persons (0.7%) fulfilled the ARA criteria for classical and definite rheumatoid arthritis, one fulfilled four criteria (probable RA). However, only 0.4% of the investigated population had more severe disease.