A significant percentage of persons who react positively to serological tests for syphilis (STS) do not have syphilis but are referred to as chronic biologic false-positive (BFP) reactors. The author studied 192 BFP reactors. Most of them were apparently healthy and had submitted to the STS in the course of premarital, prenatal, or preemployment examinations, but others had various diseases, including two cases of systemic lupus erythematosus (SLE). The clinical course of these BFP reactors has been significant, since the group includes 14 who now have SLE and 3 who have since developed Hashimoto's thyroiditis. The marked predominance of women in this series of BFP reactors was not explained by any discernible bias in the sample.