The effects of tampon composition, inoculum size, and simulated menses on production of toxic shock syndrome toxin 1 (TSST-1) and toxic shock syndrome (TSS) were evaluated in a rabbit model that simulates tampon use in humans. Three small generic compressed-fiber tampons were successively inserted vaginally (remained in place 4.5 hours x 2; overnight x 1). Tampon no. 1 was inoculated with live TSST-1-positive staphylococci plus 5 mL of saline or simulated menses (defibrinated rabbit blood plus 2.5 g of bovine serum albumin/dL) immediately after insertion; saline or simulated menses alone were used with tampons no. 2 and 3. The vagina was washed after removal of tampon no. 3. TSS-like illness was produced consistently in animals with carboxymethyl cellulose/polyester foam tampons, which supported higher organism counts and greater TSST-1 production in association with subsequent tampons. Cotton and rayon tampons were not associated with as much clinical illness, organism growth, or TSST-1 production. Simulated menses supported toxin production and clinical illness when the inoculum was one-tenth that required for controls. Sham tampon insertion was associated with TSS-like illness in two of 10 rabbits; thus, other factors may promote TSS in the absence of vaginal tampons. This model reliability reproduces menstrual TSS, since one-time vaginal inoculation with TSST-1-positive staphylococci in the presence of blood and certain tampons leads to TSS, and may be useful in evaluating catamenial products and in understanding other factors important in TSST-1 production in vivo and the development of TSS.