In summary, the routine administration of Rh immune globulin to Rh-negative women at risk has decreased the incidence of isoimmunization from 13 per cent to less than 2 per cent. Studies have shown that with the antepartum administration of 300 micrograms of Rh immune globulin to all Rh-negative women the incidence can be decreased still further to 0.07 per cent. Careful attention must be paid to all possible antepartum sensitizing situations, such as vaginal bleeding, premature labor, amniocenteses, and extrauterine manipulations. Cost-benefit analyses do show that benefits justify the extra expense of +35 to +40 per injection. The benefits and costs of routine Du typing versus its elimination for more sensitive testing remains somewhat controversial at this point.