The reproductive organs of wild and park female Fallow deer have been examined. The deer appear to breed for the first time in their second year when they are about 16 months old; none of the fawns examined was pregnant. All the adult deer had ovulated and about 95% were pregnant. It is concluded that most adult Fallow deer breed each year. The only difference found between wild and park deer was in the incidence of transmigration of the ovum; this being 52% and 28% respectively.