Undergraauate women were shown erotic and nonerotic films. A vaginal photoplethysmograph was developed and used to measure pressure pulse and vaginal blood volume during film presentations. All subjects yielded a visible increase in pressure pulse amplitude during the presentation of the erotic films. Statistical analyses of the pressure pulse data strongly confirmed (p <0.001) the visual impressions. In addition, total blood volume in the vaginal wall also increased (p <0.005) during the presentation of the erotic film. Subjective ratings of sexual arousal did not correlate with physiological measures. The results indicate that a simple and reliable device for measuring vaginal pressure pulse and blood volume is available. Measures obtained from the device appear to be useful for detecting sexual arousal in women.