The Authors report the data relative to the monitoring of menstrual cycle carried out by the observation of salivary ferning. They compared the usual physical and hormonal parameters of four groups of women with the aspect of the crystallisation of the saliva observed both by normal optical microscope and by a special type of pocket microscope which can be used by women themselves. In conclusion the Authors report a careful examination of the biochemical correlation relating the women's hormonal climate and its salivary constituents.