Fifty-two women, aged from 25 to 41 years, with infertility due to chronic anovulation were admitted to the study together with 36 age-matched controls with proven ovulatory cycles. Paired plasma (3 ml) and whole unstimulated saliva (10 ml) samples were collected over a 30 day period, starting from the first day of a menstrual bleeding, in patients, and throughout the menstrual cycle, in controls. Salivary progesterone levels, measured in women with infertility, ranged from undetectable values to 16 pmol/l during the first, and from 36 to 98 pmol/l during the second half of the monitoring period. In eugonadal women the steroid levels ranged from 34 to 46 pmol/l and from 96 to 780 pmol/l during the follicular and luteal phases, respectively. The saliva/plasma progesterone ratio ranged from 0.58 to 2.71 p. cent and a good correlation between salivary and plasma levels was found at each time of monitoring. Many (86 p. cent) of patients, which were randomly allocated to a low- or high-dose epimestrol administration schedule, appeared to be sensitive to the drug, achieving, after therapy, salivary progesterone levels which were within the range of controls. Since correct assessment of luteal function in basal conditions and during therapy requires multiple steroid measurements, and since saliva can be obtained by non-invasive techniques, salivary assays represent an attractive alternative to plasma ones for monitoring ovarian activity, also during specific treatment.