The circulating level of ACTH (by radioimmunoassay) and curtisol (by competitive protein binding) were determined at 1− to 2-hour intervals during spontaneous labor (N = 8) and induced labor (N = 28) and after delivery. There were no differences in ACTH levels between primiparous and multiparous women. The primiparous women displayed a higher level of cortisol throughout labor than the multiparous women, but not after delivery. After spontaneous onset of labor, ACTH levels were always lower than after elective induction of labor, while there were no differences in the levels of cortisol. The hypertensive complications of pregnancy did not affect the secretion of ACTH. In normal pregnancy the rise of cortisol during labor and after delivery was significant, but it was not significant in the group of patients with hypertensive complications.