LTA, SMA and ANA were found at higher frequencies in sera from NPC patients than in those from matched controls. The frequency and GMTs of LTA-positive sera varied with the origin of the patient (Chinese greater than North African greater than Caucasian, thus paralleling the risk for NPC in each ethnic group) and the stage of the disease (stage IV greater than stage I). A positive correlation was found between LTA and anti-EBV titres with regard to anti-VCA and anti-EBNA antibodies. SMA were specific for actin, and their titres did not correlate with anti-EBV (VCA, EBNA and EA) titres. Although there was no evidence for an abnormal immunogenicity of the self components recognized by the three autoantibodies, their independent augmentations did not favour the alternative hypothesis of a common central mechanism for their production. The origin and the biological significance of these autoantibodies remains, therefore, to be explained.