Haiseiko (ハイセイコー, Haiseikō) (March 6, 1970 - May 4, 2000) was a Japanese Thoroughbred racehorse.In 1972, at age two, Haiseiko began racing at the Oi Racecourse for the Japanese National Association of Racing. He was undefeated in six starts at Oi Racecourse. The race called the Seiun Sho which he won is today known as the Haiseiko Kinen.At age three, Haiseiko was traded to the Japan Racing Association.