The original Microbiology course had started in 1911 according to the use of  the first light microscope. In 1912 the Division of Germ Investigation was announced to be a laboratory for investigating  patients’ blood and urine specimens. In addition, the Bacteriology course including lectures and laboratory classes began. Later on, Bacteriology course was a part of Pathology course. At the cerebration of Siriraj Hospital’s 50th anniversary in 1939, the Pathology Department showed the exhibition on certain viral infection diseases. In 1953 the Microbiology course was devided into four sections including Bacteriology, Mycology, Virology and Immunology. In 1964 the Microbiology Department was officially independent from Department of Pathology.

     Microbiology Building had been constructed during 1972-1978 and then shared by Microbiology Department as well as Department of Clinical Pathology. During 1982-1992 certain Divisions of Mahidol University, i.e., ‘Division of Academic Affairs’, ‘Division of Students Affairs’,  ‘Institute for Languages and Cultures’ and  ‘Faculty of Graduate Studies’ temporary permitted to use some spaces of Microbiology Building. A 400 seats auditorium with a large hall had been used as medical student lecture room and academic conferences of Faculty of Medicine Siriraj Hospital. In November 1993, Faculty of Medicine Siriraj Hospital approved and named the auditorium “Sukhum Pattrakhom” in honor of the first Chairman of the Department of Microbiology, who passed away in 1992. After the Faculty of Graduate Studies moved to the Building of the Office of the President, Mahidol University at Salaya, the west-wing of the 5th floor was renovated to use as ‘The Center of Molecular Medicine’ and  ‘Office for Research and Development’.

     When the construction of the Adulyadej Vikrom Building on the old Pathology Building area began in 1993, Department of Pathology was temporary moved to the Microbiology Building on the extended 7th floor. In addition, the electron microscopy room was also moved to the first floor of the building. Currently, the Departments of Pathology and Immunology and Office for Research and Development have located on the Adulyadej Vikrom Building. Microbiology Building presently includes the Department of Clinical Pathology on the 1st and 2nd floors, as well as the Department of Microbiology from 3rd to 7th floors. The Central Laboratory of Department of Microbiology is on the 3rd floor with well equipped online system and ‘closed-circuit’ televisions. Apart from these facilities, each floor has rooms for small group teaching and meeting.

     Department of Microbiology is officially named in 1969. Since 1964 till present, 8 Chairpersons have been elected as followed:

1.	Prof.Dr.Sukhum Pattrakhom	1964-1977
2.	Prof.Dr. Padaeng Palangkul	1977-1980
3.	Prof.Dr. Prasert Thongcharoen	1980-1987
4.	Prof.Dr. Sopon Kongsamrarn	1987-1991
5.	Assoc.Prof.Dr. Prayad Tassanakorn	1991-1993
6.	Assoc.Prof.Dr. Chantapong Wasi	1993-1997
7.	Assoc.Prof.Dr. Chertsak Dhiraputra	1997-2004
8.	Prof.Dr. Ruengpung Sutthent	2004 until today’s date

     The first Chairperson was a very talent medical doctor, who also received his Ph.D from University of Washington, USA,  had organized and divided the Department into four separate Sections including Bacteriology, Mycology, Virology, and Immunolgy with Prof.Dr. Sopon Kongsamrarn, Asscoc.Prof.Dr. Prayad Tassanakorn, Prof.Dr. Prasert Thongcharoen, and Dr. Pirach Panpat acting as Chief of each section, respectively. In August 1993 Immunology Section was annouced as Department of Immunology with the first Chairman, Prof.Dr. Sutthipant Sarasombath.