During an investigation of the surface microflora of Stilton cheese during ripening, Brindley(1) isolated lactobacilli from the surface scrapings of normal and slipcoat cheese. Some of these isolates were sent to the National Institute for Research in Dairying to form part of a collection of lactobacilli which was being built up for classification purposes. During the work on classifying lactobacilli these organisms from Stilton cheese were examined and all but one were serologically grouped and identified by physiological tests. They were also tested against a number of type sera which were available, and it was found that, although isolated fromcheese of different origins, most of the strains belonged to the same serological type.