The author has studied histochemically on the giant cells appeqring in the 10 giant cell lesions which had been collected from the biopsies at the deaprtment of oral pathology, college of dentistry, Seoul national university and dental sections of several hospitals in Seoul. The results obtained were as follows: 1. The giant cells varied in size had 2 to 10 nuclei without any mitotic figures. 2. The giant cells showed high granularity in cytoplasm, extreme irregularity in outline of nuclear and cytoplasmic membrane, and very large and prominent nucleoli. 3. The giant cells were reacted moderately by Periodic Acid-Schiff raction. 4. The chtoplams of giant cells were stained moderately of deeply with Pyronin, and their nuclei with Methyl green. 5. In the sections stained with Iron-Hematoxylin, the giant cells showed microvacules and fine granular type mitochondria aggregated close to nuclei but not phagocytosed materials.