Fifteen pregnant goats serologically negative for Toxoplasma gondii were inoculated orally with 10, 100, or 1,000 infective oocysts of the GT-1 strain of T gondii. Four goats received 10 oocysts, 6 received 100 oocysts, and 5 received 1,000 oocysts. Six pregnant goats served as noninoculated controls. All inoculated goats became pyretic (40-41 C) and were dyspneic between 4 and 12 days after inoculation (DAI). Two goats inoculated in early pregnancy (68 and 70 days) with 100 oocysts had enlarged uteri; fetal membranes but no fetuses were found when they were killed 86 and 88 DAI. Three goats aborted or had a stillborn kid 9, 10, and 11 DAI. The remaining 10 goats delivered kids infected with T gondii; 8 goats had at least 1 stillborn kid, and 2 goats had infected but otherwise normal kids at birth. Placenta and tissues of fetuses and kids were inoculated into mice for determination of Toxoplasma infectivity. Toxoplasma gondii was isolated from the fetal placenta of 6 of 7 goats as early as 10 DAI and as late as 62 DAI. The organism was isolated from every fetus or kid that was born 18 DAI but not from fetuses or kids born 9, 10, and 11 DAI. Two kids were born 15 DAI; T gondii was isolated from 1 kid but not from the other, suggesting that T gondii invaded fetal tissues between 11 and 15 DAI. Of the 20 transplacentally infected kids, T gondii was isolated more frequently from the skeletal muscle, heart, lung, and brain than from other tissues.