Abstract.In the years 1975–1976, 6, 766 unselected (ABO compatible and incompatible) primigravidae parturients with uncomplicated delivery were given 100 μg (250 IU) anti‐D IgG. A total of 4,473 presented for the 6‐month control examination. IAGT was positive in 5 cases (0.11%). The 200 μg (500 IU) dose was administered to 1,543 women. Of these, 962 presented for serological control. IAGT was positive in 1 case (0.10%). The difference is not significant. The findings support the results of previous studies suggesting that 100 μg anti‐D is a sufficient dose to prevent immunization in uncomplicated