OBJECTIVE: To establish age-stratified reference values for salivary luteal P levels. DESIGN: One hundred thirty-six regularly menstruating women (18 to 48 years of age), screened for weight, exercise, and steroid medication use, collected daily saliva samples for one complete menstrual cycle. Luteal P levels were measured by 3H-RIA, and data were aligned by day of next menstrual onset. Means (+/- 1 SD range) and percentiles, calculated using both untransformed and log transformed data, were calculated for each luteal day and for indices of luteal P production. RESULTS: Reference values for salivary daily luteal P levels and indices of luteal P are presented for three age groups (18 to 24 years, 25 to 39 years, and 40 to 48 years). CONCLUSION: The age-stratified reference values presented here can be used, without collateral clinical procedures, to assess salivary luteal P levels. Salivary monitoring is ideally suited for research and long-term clinical observation, but the characteristics of salivary P data may limit the usefulness of these values for individual diagnosis.