The effect of iron supplementation alone or in combination with ascorbic acid as a preventive and or corrective measure against anemia were tested using pregnant women seeking pre-natal consultation at various health centers in Greater Manila Area. One tablet containing 65 mg iron alone or in combination with ascorbic acid per day during a supplementation period which varied from 16.5 to 17.8 weeks maintained initial hemoglobin and hematocrit levels in non-anemic women. Three tablets of the same iron preparation (total of 195 mg iron) daily resulted in significant increases in hemoglobin and hematocrit in anemic women. Ascorbic acid had no apparent beneficial effect. Considering the positive response to iron treatment, it is recommended that a nationwide program of iron supplementation of pregnant Filipinos be undertaken.