OBJECTIVE The authors assessed to what extent the commonly used the magnetic resonance imaging contrast agent, gadopentetate dimeglumine, crosses the placenta. METHODS Eight pregnant rabbits in the third trimester were injected with 0.1 mmol/kg of gadopentetate dimeglumine, and killed 5, 15, 30, or 60 minutes after injection. Placental and fetal tissues were analyzed for gadolinium content. RESULTS Placental concentrations of gadolinium were initially high (16.6 +/- 3.4 micrograms/gram) and then declined with a biexponential pattern. Initial gadolinium levels in the fetal organs were low and remained so except for the fetal kidneys, which showed increased levels of gadolinium from 4.3 +/- 1.1 micrograms/gram at 5 minutes to 6.8 +/- 1.8 micrograms/gram at 60 minutes. CONCLUSIONS The results indicate that gadolinium does cross the rabbit placenta, and that concentrations in the placenta and the fetal urinary tract are sufficient for imaging as well as possible fetal toxicity.