The hormonal profiles for oestradiol-17 beta, progesterone, prolactin and beta-human chorionic gonadotrophin (beta-hCG) are documented for the first 24 pregnancies arising from in-vitro fertilization during a collaborative project between the University of Western Australia and PIVET Laboratory. All patients had ovarian follicle stimulation with clomiphene citrate, sometimes combined with human menopausal gonadotrophin and all had oocyte recovery undertaken 36 h after injection of 5000 i.u. hCG. The follicular phase profile indicated that patients were admitted for the hCG injection when oestradiol-17 beta levels were around 1500 pmol/l per follicle with a dimension of greater than or equal to 1.6 cm on ultrasound. Luteal phase data indicated that oestradiol-17 beta and progesterone levels were two to three times higher than that expected during spontaneous conception cycles and those pregnancies which subsequently aborted had significantly lower levels in the late luteal phase. During pregnancy elevated oestradiol-17 beta and progesterone levels were maintained through the early weeks during organogenesis while the beta-hCG profile was similar to that reported for spontaneous pregnancies arising without ovarian stimulation. Six women aborted and the other 18 pregnancies have generated 22 infants.