Timed-pregnant Fischer 344 rats and New Zealand White rabbits were exposed to ethylene glycol monobutyl ether vapors by inhalation on gestational days 6 through 15 (rats) or 6 through 18 (rabbits) at concentrations of 0, 25, 50, 100 or 200 ppm. The animals were sacrificed on gestational day 21 (rats) or 29 (rabbits). In rats, exposure to 200 or 100 ppm resulted in maternal toxicity (clinical signs, decreased body weight and weight gain, decreased absolute and relative organ weights, decreased food and water consumption and evidence of anemia), embryotoxicity (increased number of totally resorbed litters and decreased number of viable implantations per litter) and fetotoxicity (reductions in skeletal ossification). No increase in fetal malformations was observed in any exposure group relative to controls. At 50 or 25 ppm, there was no maternal, embryo or fetal toxicity (including malformations) in rats. In rabbits, exposure to 200 ppm resulted in maternal toxicity (apparent exposure-related increases in deaths and abortions, clinical signs, decreased weight during exposure and reduced gravid uterine weight at sacrifice) and embryotoxicity (reduced number of total and viable implantations per litter). No treatment-related fetotoxicity was seen. No treatment-related increased in fetal malformations or variations were seen at any exposure concentration tested. There was no evidence of maternal, embryo, or fetal toxicity (including malformations) at 100, 50 or 25 ppm in rabbits.