Severe iron-deficient anemia was produced in the rat by diet. Controls consisted of animals raised on the same diet but injected with iron intraperitoneally. The deficient rats were bred and found to have normal numbers of corpora leutea of pregnancy and implantation sites. Resorptions were very common, and only about 25% of the deficient fetuses were viable on day 20. The peak mortality occurred on about day 12 of gestation. The viable fetuses were smaller than the controls, and a predominance of females was found. More eye defects occurred in the deficient groups, but a significantly increased gross defect rate over controls did not occur. The deficient maternal hemoglobins dropped during pregnancy, and the maternal and fetal hemoglobins on day 20 of gestation averaged 4.5 and 4.7 gm/dl, respectively. Partial treatment of the deficient animals by iron injection on days 0 and 7, or on day 7, prevented embryonic and fetal loss and partially corrected both fetal and maternal hemoglobin concentrations.