Mycotoxins are chemicals produced by fungus and many of them are toxic to humans. Zeranol is a mycotoxin used to promote growth in cattle in North America; yet such a practice draws concern about the residual compound in meat in European countries. In the present study, the toxicity of zeranol was tested in a mouse model for reproduction. Pregnant ICR mice were given p.o. daily doses of zeranol at 0, 1, 10, 100 mg/kg for 4 days (from E13.5 to E16.5). Increased rates of fetal resorption at late gestation (E17.5) and preterm birth (