The prevalence of perimenstrual symptoms usually is based on reports for one menstrual cycle; the consistency of symptoms across cycles is ignored. The purpose of this investigation was to determine perimenstrual symptoms reported concordantly for two menstrual cycles in a group of 63 presumably healthy women reporting symptoms in health diaries over 2 months. There were only nine symptoms for each of the menstrual and premenstrual phases reported by the same woman across both cycles. Furthermore, concordance of perimenstrual symptom reporting across the two cycles was significant only for backache (κ = .636, p < .0001), headache (κ = .849, p < .001), and cramps (κ = .899, p < .0001) in the menstruum and for backache (κ = 0.123, p < .0001), cold sweats (κ = .500, p < .0001), fatigue (κ = .135, p < .0001), depression (κ = .268, p < .0002), and tension (κ = .320, p < .0001) in the premenstruum. Several symptoms showed high prevalence during the remainder of the cycle which might contribute to the lack of concordance. These data imply that prevalence estimates based on only one menstrual cycle may be inaccurate overall and inadequate as baseline or followup estimates by which to evaluate therapeutic intervention.