1. The concentrations of phylloquinone (PK) and menaquinone-4 in various tissues of wild and cultured sardine were measured with HPLC methods. 2. The major vitamin K in wild sardine was phylloquinone. The stomach and intestinal contents of wild sardine, as well as plankton (which may be consumed by wild sardine), showed a much higher level of PK than of menaquinone-4. 3. Cultured sardine fed a menadione-supplemented feed were rich in menaquinone-4, which indicates that menadione was converted to menaquinone-4 in the body. 4. These results suggest that either PK or menaquinone-4 deposited in the body are derived from food and stored mainly in the liver.