From this composite picture of the history and recent developments related to TSS, several points are clear. TSS is not a new disease, and TST-producing strains of S. aureus are not new. What is new is the recent dramatic increase of this disease in young women who use tampons during menses and who lack antibody to TST. What is also new is the recognition that the disease commonly recurs but only in menstrually associated cases. What remains to be determined are the precise role of tampons, the factors leading to toxin induction, and the mechanism of action of this potent toxin. In order to better determine what these factors and mechanism of action are, and to determine if the TST marker protein is in fact the critical toxin, a reliable animal model is badly needed. Finally, a reliable laboratory test to confirm the clinical diagnosis is another high-priority need. The further unraveling of the secrets of this complex disease may greatly enhance our understanding of the disease associated with this toxin, of the intricacies of toxin production by other bacteria, and of the role that exogenous cofactors play in disease processes.