Fourteen women had specimens collected from their nares, hands, vaginal vestibule, and vagina. Samples were taken the week before, during, and the week after menstruation during three menstrual cycles for a total of nine specimens from each location. Qualitative and quantitative studies were done on the vaginal specimens; the other specimens were examined specifically for Staphylococcus aureus. The premenstrual specimens averaged the highest number of bacteria (approximately 10(9)/mL) but the lowest number of different species (approximately 11). The menstrual specimens averaged the lowest total number of bacteria (approximately 4.0 x 10(7)/mL) but the highest average of different species (approximately 14). The highest rate of positive cultures was for the nares, 34%; followed by vaginal vestibule, 20%; vagina, 19%; and hands, 4%. The nine sequential location samples showed the following percentages of S. aureus: nares, 57%; hands, 29%; vaginal vestibule, 57%; and vagina, 64%.