The purpose of this study was to evaluate the direct effect(s) of in vitro cadmium (Cd) exposure on steroidogenesis in rat ovaries during different reproductive states. Sprague-Dawley rats were killed on the day of proestrus, or on gestation day 6 or 16, Ovaries were removed, placed in medium and minced, Culture from each ovary was incubated with Cd2+ ions in concentrations of 0, 100, 500, 1000, 1500, or 2000 mu M. One-hour whole-ovary production of progesterone (P-4), testosterone and estradiol (E-2) in culture medium was evaluated in the absence and presence of human chorionic gonadotropin (hCG) or hCG plus pregnenolone by specific radioimmunoassay, Under in vitro Cd exposure the most affected were productions of P-4 and testosterone in proestrus rats and less in pregnant dams, whereas E-2 was not affected at all. Cadmium appears to interfere with the ovarian steroidogenic pathway in rats at more than one site. Copyright (C) 1999 John Wiley & Sons, Ltd.