Studies were done to compare tampons made solely of cotton and made of both cotton and rayon for effect on growth of Staphylococcus aureus and production of toxic shock syndrome toxin-1 (TSST-1). Under stationary in vitro conditions in which tampons were either oversaturated or 50% saturated with culture media, the same amount of or more TSST-1 was made with cotton tampons than with cotton/rayon tampons. Similarly, when tested with the tampon sac method, cotton tampons yielded the same amount of or more toxin than did the cotton/rayon tampons. Bacterial cell numbers generally paralleled toxin production. These data indicate that cotton tampons neither prevent TSST-1 production nor significantly adsorb toxin onto the fibers to make toxin unavailable to cause toxic shock syndrome, in contrast to results of a previous study.