The effect of ochratoxin A (OA) on fertility and embryo viability was studied in wild-type Japanese quail. Adult male and female birds were fed either 0 or 16 ppm OA for 9 wk. Eggs were set daily, incubated for 7 days, and examined macroscopically for both fertility and viability. Fertility was not affected by treatment. Eggs from females receiving 16 ppm OA had significantly (P < 0.05) higher percentages of early embryonic deaths. Histopathological examination did not detect any adverse effect of OA on spermatogenic activity. In an in vitro study, fertile eggs were injected with graded doses of OA, incubated for 7 days, and examined macroscopically for viability. The percentage of early embryonic deaths in eggs injected with either 1600 or 5000 ng O A per egg was similar to incidence of early embryonic death observed in the in vivo groups in which the females received 16 ppm OA in their feed. It is suggested that the embryotoxic effect of OA is exerted through the presence of OA in the egg rather than through an alteration of gametes.