Somdet Chaopraya Institute of Psychitry is the first psychiatric hospital in Thailand established by the benevolence of His Majesty King Rama V on November 1, 1889 with the name "Insane Asylum" located at Pak Klong San. The Insane Asylum provided medical treatment for patients by physicians and Thai traditional physicians. Later, number of patients became increased yet the space remained limited. Dr. Heighed, Chief sanitary doctor Metropolitan Ministries and the first director of the hospital, had proposed the government to buy the land and house belonged to Chao Pra Ya Sura Wong Wai Wat (Worn Bunnag) or Chao Khun Thahan, the land belonged to Mr. Pia Ra Chanu Praphat and nearby area altogether of 44 rai and a half to build a new hospital which was in the location of the present institute. The hospital was located at the western edge of Klong San approximately 600 meters away from the old one. The construction of Insane Asylum was under the control of Lord Ayurawet Wi Chak (Dr.Catthew), the assistant of sanitation department. He was well regarded from building the true foundation of a westernized psychiatric hospital by providing treatment according to modern knowledge, as well as patient care with compassion and humane. The environment of the hospital had large shady trees with beautifully colorful flowers and leaves, the patient rooms had steel bars with lotus stem shape, no windows yet open, and red tin roof.
Later, the hospital was administered by graduated Thai modern physicians. Professor Wichian Phaetthaya Khom (Dr. Thian Tu Wichian) had been appointed as the first Thai hospital director after his two years strudy in psychiatry from the United States. Realizing the importance of psychiatric care and sharing his knowledge by through articles, lectures, and speeches in order to ensure people understanding and put an end to dread towards psychiatric patients. He granted the hospital the new name, "Thonburi Psychiatric Hospital", instead of "Insane Asylum", in 1932 to relieve the general disgust of people toward the mentally ills.
Dr.Saifon Sang Sing Kaew, a director during the year 1942-1959, was regarded as being the father of psychiatry in Thailand. He renovated the hospital by putting up the screens and removing all steel bars, changing the name of the wards to those of flowers for pleasant meaning, employing love into patient care, and treating patients as parents would their children. In academic aspect, he laid the foundations of pre- and post-graduation in psychiatry and mental health. He renamed the hospital to "Somdej Chaopraya Hospital" in 1956 as per Somdej Chaopraya road which passes in front of the hospital to mitigate patient humiliation.
Somdej Chaopraya Hospital offers treatment and care for psychiatric, neurological, neurosurgical, and neuropsychiatric patients. The hospital is a training institute for psychiatry, mental health and health-related of pre- and post-graduate levels in order to develop academic activities in mental health, neurology, neurosurgery, psychiatry, and neuropsychiatry. Complying with the duties and responsibilities appointed to the hospital, it has been renamed to "Somdet Chaopraya Institute of Psychiatry" in 2002.