Since late 1979 to early 1980, when toxic shock syndrome achieved notoriety, a substantial body of data has demonstrated that vaginal Staphylococcus aureus infections, particularly those occurring during menstruation, account for most cases of toxic shock syndrome in women of reproductive age. Among those patients with onset during menstruation, tampon use has been identified as the most important risk factor. Although menstrually associated cases have been observed among users of all brands and styles of tampons, the use of selected "super absorbent" brands and styles has been associated with an increased risk of toxic shock syndrome. Although the tampon characteristics responsible for the associated risk of toxic shock syndrome remain poorly understood, both absorbency and chemical composition appear to be important variables in this relationship. In response to studies demonstrating this relationship and legal pressures, tampon manufacturers have removed chemical constituents previously used to enhance absorbency, such as polyester foam, carboxymethylcellulose, and polyacrylate rayon, and have markedly reduced tampon absorbency. Coinciding with these changes, the reported number of menstrually related cases of toxic shock syndrome has dropped substantially, although they continue to account for 50% to 70% of all cases of toxic shock syndrome in women of reproductive age.