Although the effect of vaginal tampons on microbial flora during menstruation has been studied, the effects attributable to particular tampon fibers have received inadequate attention. The purpose of this report is to review previous studies and describe the results of laboratory tests that compare the effects of use of various tampons on the normal changes that occur in vaginal microflora during menstruation. Tampon and swab samples were obtained from volunteers on days 2, 4, and 21 after the start of menses. Statistical evaluation of the qualitative and quantitative data revealed that the same numerically dominant phenotypes were present regardless of sample type, sample time, or catamenial product. In general, total bacterial counts decreased during menstruation, and the total bacterial counts from tampon samples tended to be lower than those in concomitant swab samples. Predictable changes in total numbers of the dominant species were noted when the data were evaluated by day of menstrual cycle. Results indicate that the tampon type had little effect on the qualitative and quantitative composition of the vaginal microflora during the menstrual cycle.