The type strain of Streptococcus mitis, strain NCTC 3165 (= ATCC 33399), does not fit the description of the species, and it is genetically unrelated to reference strains that do conform to the description. Strain NCTC 3165, which was deposited as S. mitis in 1930, does fit the description of Streptococcus sanguis White and Niven (1946) and was recognized as a S. sanguis strain by authors of reports that were published prior to 1980, when this reference strain was elevated to the type strain of S. mitis. Streptococcus oralis Bridge and Sneath (1982) fits the description of S. mitis, and its type strain, strain NCTC 11427, is genetically homologous with reference strains that fit the description of S. mitis. S. oralis has the same cell wall characteristics that have been described for S. mitis ("S. mitior"). I propose that S. oralis be considered a later synonym of S. mitis and that the type strain of S. oralis be adopted as the type strain of S. mitis.