The Department of Bacteriology (1935-1968) at Brigham Young University was an academic instructional unit.

The Department of Bacteriology was established in 1934 as part of the College of Applied Science, and was responsible for teaching bacteriology, soil microbiology, sanitation, public health, and related courses. In 1954 it was moved to College of Biological and Agricultural Sciences. The department was renamed the Department of Microbiology in 1968. Department chairmen included Thomas L. Martin (1935-1949), Dean A. Anderson (1950), Jay V. Beck (1951-1954), Don H. Larsen (1955-1958), David M. Donaldson (1959-1960), Richard D. Sagers (1961-1965), and Don H. Larsen (1966-1968).

The Department of Microbiology (1968-2003) was created under the College of Biological and Agricultural Sciences to provide instruction in the field of biology at a microscopic level.

The Department of Microbiology included courses on introductory microbiology, sanitation and public health, general microbiology laboratory, food microbiology, dairy microbiology, applied clinical diagnosis laboratory, epidemiology, bacterial physiology, pathogenic microbiology, immunology, industrial microbiology, virology, cell and tissue culture techniques, radioactive tracer techniques in biology, and microbial genetics.

The department was administered by a department chair, under direction of the college dean. The department was associated with a number of colleges during its history, including the College of Biological and Agricultural Sciences (1968-1983) and the College of Biology and Agriculture (1983-2003). Department chairmen included: Don H. Larsen (1968-1971), David M. Donaldson (1972-78), Richard D. Sagers (1979-1983), James A. North (83-89), Donald N. Wright (1989-1998), and Sauna C. Anderson (1998-2002).

The Department of Microbiology and Molecular Biology (est. 2003) was created under the College of Biology and Agriculture and focuses on the study of microscopic organisms.

The Department of Microbiology and Molecular Biology offered majors in clinical laboratory science, microbiology, and molecular biology. Minors included microbiology and molecular biology. Undergraduate courses included: clinical laboratory techniques, general microbiology, microbial genetics, microbial physiology, immunology, medical microbiology, virology, microbial ecology, hematology, immunohematology and coagulation theory, practical hematology, medical parasitology, pathophysiology and laboratory diagnosis in clinical chemistry, and concept application in laboratory medicine.

The department was administered by a department chair, under direction of the college dean. The department was associated with a number of colleges during its history, including the College of Biology and Agriculture (2003-2007) and the College of Life Sciences (2007-). Department chairmen included Alan R. Harker (2002-2005), Brent L. Nielsen (2005-2011), and Laura C. Bridgewater (2011- ).