Groups of 6 mated female Sprague-Dawley derived rats were treated orally with o-nitroaniline (lot no. 1769150) at dosages of 50, 200, 400, 800, and 1200 milligrams/kilogram body weight on days 6 through 15 of gestation. A vehicle (corn oil) control group received corn oil on a comparable regimen. Animals were observed daily for mortality or signs of toxicity. Maternal body weights were recorded at intervals throughout the study. On day 21 of gestation, all surviving females were sacrificed, the number of. corpora lutea were determined, and the uterine horns were examined for implantation sites, resorptions, and the number of viable or nonviable fetuses. The sex and weight of each live fetus was recorded. All fetuses were examined for external malformations.