ABSTRACTMenstrual cycle effects on erotic arousability were tested in 13 women aged 20–28. Vaginal blood volume and pulse amplitude were measured with a light emitting diode photoplethysmograph, labial temperature was measured by a small thermistor, and subject self‐report of arousal was estimated on a 7‐point Likert scale in response to audio erotic tapes and fantasy over five different phases of the menstrual cycle. Pre‐session levels of blood volume and labial temperature showed no important changes across the cycle, but pooled blood volume, pulsatile blood volume and labial temperature reliably demonstrated sexual arousal during tape and fantasy sessions. Repeated measures analyses of variance and covariance of physiological change scores from baseline and subjective ratings failed to demonstrate that significant changes in self‐reports, vaginal blood volume, vaginal pulse amplitude, or labial temperature occurred as a function of menstrual cycle phase. This study provides objective physiological evidence that there appears to be no one phase in the menstrual cycle during which women are more sexually arousable to erotic stimuli as detected by these physiological