Abstract
The haematological and obstetric details of five women with Addisonian pernicious anaemia and infertility are described together with those of another patient who developed the anaemia soon after confinement. The implications are discussed, and it is concluded that the prophylactic administration of small doses of folic acid during pregnancy is a safe procedure while the risk of precipitating subacute combined degeneration of the cord in undiagnosed Addisonian pernicious anaemia is hypothetical. Although the mechanism of the infertility in pernicious anaemia remains undefined, several factors which may be of aetiological significance are considered.