Megaloblastic anemia is due to the deficiency of folic acid and vitamin B12. In the developing world incidence is as high as 25%. The molecular basis for megaloblastic anemia is failure of the synthesis and assembly of DNA due to the deficiency of folic acid and vitamin B12. Inadequate intake, increased demand and impaired absorption are main causes of the deficiency. The basic workup includes peripheral blood smear, serum folate level and serum B12 estimation. Peripheral smear should have at least two of the following features in the films of the buffy coat layer: More than 4% of neutrophil polymorphs with 5 or more lobes, Orthochromatic macrocytes, Howell-Jolly bodies, nucleated red cells, macropolycytes. The fasting serum folate level is less than 6 µg /L and RBC folate is less than 165 µg/L. Red blood cell folate is the test of choice for the diagnosis of the deficiency. In vitamin B12 deficiency, serum vitamin B12 is less than 190 µg/L. The Schilling test, which is used to assess the causes of malabsorption of vitamin B, is usually done after delivery in the postpartum period. Treatment includes folic acid, 1 mg tid orally, vitamin B12, 6 weekly injections of 1 mg of cyanocobalamin and iron supplementation. Severely anemic women at term may need blood transfusion followed by parenteral therapy with folic acid, 1 mg/day for 1 week and cyanocobalamin, 100 µg/day for 1 week.