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I read with great interest the epidemiological study of rheumatoid arthritis (RA) in Hungary1. However, 2 points need to be clarified. Firstly, the authors interviewed 10,000 inhabitants with a refusal rate of 21.5%. These 2150 persons are not seen in Figure 1. The last point is that if you survey 10,000 inhabitants and find 13 patients with RA the prevalence of RA will be simply 0.13%[10/5515 (0.18%) in women; 3/4485 (0.06%) in men] instead of 0.37%(0.48% and 0.23% in women and men, respectively) even if those who have refused are excluded.