A cohort of 59 initially healthy subjects with chronic false-positive seroreactions for syphilis was followed for 3 to 19 years (mean 13 years) by data linkage to computerized population registry and to national hospital discharge registry using a unique personal identification number. One subject had moved abroad, but all others were known to be alive at the end of the follow-up period. Four subjects developed systemic lupus erythematosus and two developed rheumatoid arthritis. One subject was admitted to hospital because of protracted substernal pain, but a myocardial infarction could not be verified. This case corresponds to the expected number of cardiovascular events in the cohort. A chronic false positive seroreaction for syphilis was calculated to represent a hundred-fold risk for the development of systemic lupus, but such seroreactions did not seem to predict an excess of cardiovascular diseases.