The first study was done in which vaginal hormonal cytograms were correlated with cervical mucus symptoms as charted by women using the ovulation method of natural family planning. Daily vaginal smears obtained by 67 women during 78 menstrual cycles provided the basis of the study. The women had used the ovulation method for at least three cycles and were not breast-feeding. All vaginal smears examined cytologically had a microbiologic diagnosis of lactobacilli. All the vaginal hormonal cytograms revealed ovulatory-type patterns. Karyopyknotic index (KPI) peak correlated with peak mucus day +/-2 days in 74, or 94.9%, of the cases, with a mean of peak mucus at +0.14 days. The average number of mucus days prior to the KPI peak was 6.1. Seven women also provided daily blood specimens for bioassay of luteinizing hormone (LH). KPI peaked with a mean of 0.7 days after the LH peak.