Antigenic structure remains a major focus in thyroid immunology. The genes for three major thyroid antigens--thyroglobulin, thyroid peroxidase and the thyrotropin receptor--were sequenced in the late 1980's, and epitopes for antibody and T cells have been reported within the last year. In addition, new evidence for selective use of T-cell receptor V gene segments in human thyroid infiltrates may point the way to specific immunotherapy.