The effects of ethylene glycol monoethyl ether (EGEE) were determined on development in utero. Pregnant New Zealand White rabbits were exposed to air or 160 or 617 ppm EGEE for 7 hr/day from 1 to 18 days of gestation (dg). Virgin Wistar rats were exposed to 150 or 649 ppm EGEE or air 5 days/week for the 3 weeks immediately preceding their breeding. Sperm-positive rats were subsequently exposed to air or 202 or 767 ppm EGEE for 7 hr/day from 1 to 19 dg. Group sizes were 29 to 38 per concentration for both species. Pregestational exposure of rats had no effect on mating success, and there was no effect of EGEE exposure on establishment of pregnancy in either species. Rabbits exposed to the both concentrations had decreased food intake and depressed weight gain. Exposure-related mortality occurred in the 617 ppm EGEE group of rabbits. The only toxic sign seen in rats was reduced weight gain after exposure to 767 ppm EGEE. Exposure induced high embryomortality at maternal toxic concentrations in rats and rabbits, while lower levels induced fetal growth retardation in rats but not in rabbits. Gestational exposure increased the incidence of anomalies and variations; these were primarily of soft tissues in rabbits and of skeleton in rats. Thus, significant evidence of terata, fetal growth retardation and embryomortality were induced in rabbits and rats at levels that were below or similar to those that induced maternal manifestation of toxicity. These data implicate EGEE as a teratogen.