In June and September 1980 the Centers for Disease Control (CDC) conducted two case-control studies to identify risk factors associated with menstrual toxic shock syndrome. The first study showed statistically significant associations with three variables: tampon use, continuous tampon use, and the lack of use of any birth control method. The second study showed statistically significant associations with tampon use and with the use of a single brand of tampons: Rely (Procter & Gamble). Analysis of the biases, strengths, and shortcomings of the studies suggests that the associations shown between toxic shock syndrome and tampons (Rely tampons in particular) are real and not the result of defects in study design or attendant publicity.