OBJECTIVE:To determine if HPV detection or the size of a tampon specimen is affected by the menstrual cycle. MATERIALS:Two hundred and eighty women between 18-35 years of age attending a gynaecology clinic at The Royal Women's Hospital were enrolled. Each woman completed a questionnaire on the risk factors of HPV infection and provided a tampon specimen. Specimens were analysed for the presence of HPV DNA (polymerase chain reaction with the L1 consensus primers) after the pellet volume and number of cells was assessed. RESULTS:The mean age of the 298 women enrolled in this study was 27.0 years (SD 4.5, range 18-35). Ninety two (30.9%) of the tampon specimens were positive for HPV using the L1 consensus primer. The detection of HPV DNA was not associated with the quartiles of the menstrual cycle (p = 0.32). Both the pellet volume and the number of cells from a tampon specimen were greater during the mid cycle, although this was significant for the pellet volume only (p = 0.002 and 0.1 respectively). The pellet volume was not significantly associated with other variables assessed by the questionnaire. The number of cells from a tampon specimen increased with the numbers of life time sexual partners (p = 0.02) and was higher for a single marital status (p = 0.0008). CONCLUSION:The timing of the menstrual cycle effects the size of tampon specimens but not the probability of detecting HPV DNA.