The immunohaematology results found during antenatal care from 1963-1981 were used to try to answer the question whether and how much the anti-D-prophylaxis, which was started in 1967 and was given to German and foreign pregnant women post partum or after abortion, had affected the frequency of immunization to D and other erythrocyte antigens. The results allow the following statements: 1. From 1973-3 or 4 years after the general introduction of anti-D prophylaxis-until 1981, a continuously sustained decline in the frequency of anti-D in the German pregnant women was found. This could not be found in the corresponding group of foreign pregnant mothers. 2. Additionally, a statistically significant reduction in the frequency of anti-D + C could only be found in the German group. 3. After 1973, other erythrocyte antibodies in combination with anti-D were only found sporadically. A rise in the frequency of other erythrocyte antibodies, such as anti-C, was not observed. 4. The frequency of "non-anti-D antibodies" was significantly higher in the foreigners than in the German group during the whole observation period. This was due to the significant increase in anti-Lea, anti-Leb, anti-H, anti-P1 and the nonidentifiable antibodies in the foreign group.