Prophylaxis & treatment of megaloblastic anemia associated w/ folic acid deficiency, as in the anemias of pregnancy, hemolytic anemia, exfoliative skin disease, pellagra, sprue, alcoholism & that following gastrectomy & in pernicious anemia. Prevention of neural tube defects, including spina bifida & anencephaly; to correct decreased folate levels when taking MTX, trimethoprim, sulfamethoxazole, phenytoin, OC pills. Prophylaxis & treatment of diseases eg, colorectal carcinoma, ulcerative colitis, dysplasia, sickle cell diseases, hereditary spherocytosis & homocysteinemia.