Bisphenol A (BPA) and nonylphenol (NP) are endocrine disrupting chemicals (EDCs) which induce reproductive abnormalities. While single exposure studies have been reported, few investigations of the simultaneous administration of several chemicals to animals have been conducted. The purpose of this study was to estimate the effect of gestational exposure to BPA and NP simultaneously on reproductive function. Pregnant female ICR mice were given BPA, NP or BPA plus NP by subcutaneous injection from gestational day (GD) 5 to delivery. The daily doses of BPA and NP were 1/1,000 or 1/100 the median lethal doses (LD₅₀; BPA: 2,500 mg/kg, NP: 1,231mg/kg). On postnatal day (PND) 1, the pups (F1) were thinned out to 8. On PND 42, the body weights of some F1 were recorded and they were sacrificed; the livers, testes, epididymes, ovaries, and uteri were then weighed. The remaining F1 mice were mated with non-treated heterosexual mice. On GD 17, female mice were dissected to count the total number of fetuses and dead fetuses. All NP-treated mice exhibited decreased body and testis weight on PND 42. The pregnancy rate was 100% in all treated female groups, although it declined in untreated female mice mated with male mice from some treatment groups. The average dead fetus rate changed significantly according to the dosage combination. This study shows that BPA and NP can enhance, suppress or be neutral for the effect of the other in combined exposure to BPA and NP.