Haiseiko (ハイセイコー, Haiseikō) (March 6, 1970 - May 4, 2000) was a Japanese Thoroughbred racehorse.

[1] At age three, Haiseiko was traded to the Japan Racing Association.

Retired to stud, Haiseiko sired the Tokyo Yushun winner Katsurano Haiseiko, the Satsuki Sho winner Haku Taisei, the Tokyo Derby winner King Haiseiko and Outrun Seiko.

Haiseiko was inducted in the Japan Racing Association Hall of Fame in 1984.

The last NAR race Haiseiko ran and won, the Seiun Sho, was renamed the Haiseiko Kinen [ja] in honor of the horse in 2001 after he died.