OBJECTIVE Positive direct antiglobulin tests (DAT) occur occasionally, without obvious cause, among normal blood donors. This is sometimes associated with a false-positive serologic test for syphilis. Positive DATs due to antiphospholipid antibodies (APAbs) are well documented in the antiphospholipid syndrome with systemic lupus erythematosus and the primary antiphospholipid syndrome. METHODS Using conventional haematologic and serologic methods, we tested 474,545 normal blood donors in the west of Scotland during the years 1991 through 1993. RESULTS We identified 42 normal blood donors with a positive DAT and observed three who had positive DATs and false-positive VDRL tests, all of whom expressed raised APAbs. CONCLUSIONS APAbs may be an incidental cause of positive DATs among healthy blood donors.