We report five women with Rh 'partial D' who were found to have anti-D during pregnancy. Two patients were category IVa, their red cells typing as Go(a+); one was category VI; and two had a 'partial Du' which could not be categorized. The maternal anti-D concentration increased during four of the eight pregnancies studied, but none reached significant levels. Three of six D-positive cord blood samples had a positive direct antiglobulin test (DAGT). Although one baby became jaundiced, no treatment was required. The policy in the Oxford Region for the management of patients with a weak expression of D is outlined.