The hormonal regulation of uterine adenylate cyclase (AC) was measured in the rat by radiochemical analysis. Animals made pseudopregnant by cervical stimulation were ovariectomized on Day 1 (the first appearance of leukocytes in the vaginal smear) and injected for 6 days with sesame oil, 0.1-10.0 micrograms estrone, 2.0 mg progesterone, or 1.0 microgram estrone + 2.0 mg progesterone. AC activity in ovariectomized controls remained at basal levels (2.8-3.3 pmol cAMP formed/min X mg protein). The injection of progesterone did not alter AC activity significantly, but estrone increased AC activity during Days 3-5, and the response (5-17 pmol) was dose dependent. The action of estrone was not inhibited by progesterone. The present experiments revealed: a) AC from estrone-treated rats was activated 2- to 4-fold by 10 mM NaF; b) following treatment with estrone + progesterone, AC was activated 2- to 3-fold by a trauma to the uterus; c) unlike the response to fluoride, the effect of trauma was temporally limited to Day 4; and d) when AC was activated by trauma, no further increase was elicited by NaF. The data indicated that the transient sensitivity of AC to activation by trauma on Day 4 in E+P-treated rats was identical to that in intact rats and paralleled the normal timing of uterine sensitivity to decidual induction.