Iron deficiency is the most common cause of anemia in pregnancy. Pregnant women with anemia are, in general, exclusively treated with iron supplementation. We observed that several pregnant women with anemia who were nonresponsive to iron supplementation also had vitamin B6 deficiency, and that anemia in these cases improved with the administration of vitamin B6. Our prospective study in healthy pregnant women showed that blood levels of iron, ferritin and vitamin B6, in particular, fell to the lower limit of the nonpregnant reference range by the third trimester. We conclude that it is important to take into account the deficiency of vitamin B6 besides iron in the evaluation of anemia during pregnancy.