Osawatomie State Hospital is a public psychiatric hospital in the U.S. state of Kansas, located in the city of Osawatomie, Kansas. Established by the Kansas legislature in 1863 and opened in 1866, it is the oldest operating psychiatric hospital in the state of Kansas. It has been named "Kansas Insane Asylum" and the "State Insane Asylum" but was officially changed to its present name in 1901.