The history of Department of pharmacology would be date back to 1890 when Bhatayakorn Scool, the first medical school in Thailand, was established in Siriraj Hospital. The teaching was both in modern and traditional medicine. At the beginning, the teaching of pharmacology was under the course named SuppakunYa (drug properties) which included drug indications and drug preparations. In 1892, pharmacology course was a part of the basic physiology course instructed by Dr. George B. McFarland.

            In 1922, Prince Mahidol Adulyadej was a representative of Thai government and negotiated with Rockefeller Foundation to raise medical education in Thailand. The foundation had sent Professor E.C. Albritton to improve the teaching in physiology. As soon as he was appointed as the head of the department of physiology, he started revising the content of the physiology course, which include biochemistry, physiology, and pharmacology. The laboratory section was also be added up to the course.

            Later, in 1924, pharmacology teaching was reshaped and focused only on modern medicine. All three subjects were taught under the same course in the department of physiology until 1965. On 8th November 1965, the department of pharmacology spun off to become independent department. Professor Dr. Ouay Ketusingh served as the first head of the department of pharmacology. Department of pharmacology has since become one of the  preclinical departments of Siriraj Medical School and performed basic and translational research in pharmacology.