Somdet Chaopraya Institute of Psychiatry (also known as Somdet Chao Phraya Hospital and formerly as The Mental Hospital) is a psychiatric hospital in Khlong San District of Bangkok, Thailand. Established as a mental asylum, the original building was designed by a British architect and supervised by the British physician Dr. Morden Carthew. As the first psychiatric hospital and the second oldest hospital in Thailand, the hospital became well known for being the pioneer in the country for the humane treatment of mentally ill patients.