Episodes of luteal progesterone release which have been identified from serum samples can also be observed in saliva. Components of these release episodes--amplitude, duration, and frequency--can be separated and characterized. In a sample of 16 cycle days collected from 6 normal women, pulse duration and frequency increased significantly from the early to the mid-luteal phase, and then decreased by the late luteal phase (2-4 days before menses). Pulse amplitude also increased early to mid-luteal, but continued to increase significantly into the late luteal, and did not decline until the peri-menstrual phase (0-1 days before menses). Circadian variation, previously considered unimportant for progesterone, was also observed in late luteal samples. Extension of studies of ultradian release characteristics to groups known to vary from controls in broad-scale progesterone patterns, such as young, nutritionally stressed, or exercising women, should help to elucidate the potential functional significance of fine-grained release components. Such knowledge can also inform protocols of anthropological studies which seek to identify broad progesterone patterns or to classify and compare reproductive status.