Changes in plasma levels of estradiol and progesterone and their temporal relationship with changes in mood and behavior were studied along the menstrual cycle in 17 normal women with a wide range of severity and types of premenstrual changes (PMC). Emphasizing changes in hormonal levels over time as well as their rates of change, selective clinical features of premenstrual changes were found to be positively associated with peak levels of progesterone, its rate of decrease over time, and the ratio between the rates of decrease-over-time of progesterone and estradiol levels. A time-lag of 4-7 days between changes in plasma levels of progesterone and changes in clinical features was also found. Rate of change of estradiol was somewhat associated with clinical PMC. It is suggested that the association between gonadal hormones, other biological changes, and mood should be further studied as a diversified, dynamic, time-related process.