The purpose of this study was to explore what a young general population include when they answer questions concerning the diagnosis rheumatoid arthritis (RA). Altogether 14,420 subjects answered questionnaires concerning disease history, living habits and musculoskeletal pain. They were also asked specifically if they, or any close relative, had RA. One hundred and sixteen (1.6%) men and 115 (1.6%) women reported that they had the disease. Altogether 14 (12%) men and 23 (20%) women of those answering "yes" to the RA question, were found to have the disease verified according to their hospital records. Fifty-five (25%) of the subjects who reported to have RA, were classified in their hospital records as having other defined rheumatic diseases. Our study indicates that when the general population refers to the diagnosis of RA, they include most defined rheumatic diseases as well as unspecified arthralgia. We find it interesting that such a substantial number of young people report they have this serious disease. We therefore recommend that other measures should be used or used in addition to mailed questionnaires when exploring the prevalence of RA.