Teratogenicity was evaluated in groups of pregnant Sprague-Dawley rats (25/group) receiving orthonitroaniline, orally by gavage, at concentrations of 0, 100, 300 or 600mg/kg/day on days 6 through 15 of gestation. Maternal toxicity was evident by statistical differences between dosed groups and controls for: number of cases of piloerections (mid and high dose groups), mean maternal body weights (mid and high dose groups) and food consumption (all treatment groups). Pregnancy rate and the number of live and dead fetuses, early and late resorptions, total nidations and corpora lutea were comparable for all groups. No meaningful differences in the total number of litters of fetuses exhibiting malformations was evident. However, one fetus in each of two litters at the 600mg/kg level exhibited partial situs inversus and similar heart malformations.