In albino rats fed on a synthetic diet and a nonprotein diet, and in rats with the experimental liver damage, the administration of methylmethionine sulfonium orotate supressed the decrease in body weight caused by the operative stress, and exerted a stimulating effect on healing in contraction of skin wound. Methylmethionine sulfonium orotate injection also caused a slight promotion of healing in contraction and tissue tensile strength of skin wound in adult dogs whom liver had been damaged.