Commensalism is a biological association between two species, with one species, the commensal, getting an advantage, whereas the other one, the host, gets no advantage neither disadvantage. This concept is theorized in the 1860's by Pierre-Joseph Van Beneden. Van Beneden is a physician in the 1850's, nevertheless, he is well known as a zoologist. The concept of commensalism developed by Van Beneden is employed in many scientific fields, not only in zoology, but also, in microbiology. Although the use of a possible play of the commensal bacterial microflora is exposed at the end of the 19th century, it is only during the second part of the 20th century that this way is studied. Commensalism in animal microbiology is studied first and then it is studied in human. The aim of this article is to present the history of commensalism as a main part of the history of microbiology.