The prevalence of rheumatoid factor (RF) in urban population was examined. A random sample was taken according to the register of voters and included 5% of the population. Among them 60% suffered from various rheumatic symptoms. Out of 500 persons invited to an examination, 231 examinees responded. None of the examinees in that moment showed signs of rheumatoid arthritis. RF is determined in serum according to Waaler-Rose and it was positive in 12 out of 231 examinees (5.2%) about equally in men and women (P > 0.05). The majority of examinees was over 50 years old. Titar RF increased with the age of the examinee, but difference is not significant (P > 0.05). RF is not only a characteristic of RA, but it could also be found during the other diseases which are accompanied by, first of all, hypergammaglobulinemia and fibrosis.