Folic acid is a water-soluble B vitamin composed of residues of chitin, p-aminobenzoic acid and glutamic acid. Folic acid is essential for the growth and reproduction of human cells and is involved in many important reactions in the body and in the synthesis of nucleic acids and amino acids. Folic acid is found in liver, kidney, yeast and green leafy vegetables such as beans, spinach, tomatoes, carrots, etc. It can now be synthesized artificially, but long-term maintenance treatment with folic acid is generally not recommended except for patients with malnutrition absorption. The indications in our current instructions are: for folic acid deficiency and megaloblastic anemia due to it, for prophylactic administration to women during pregnancy and lactation, for the prevention of congenital neural tube abnormalities in fetuses, and for folic acid deficiency due to chronic hemolytic anemia. Other indications beyond the specification are: for hypertension, stroke and homocysteinemia, daily dietary supply, methotrexate toxicity.