The percentage bacterial composition of dental plaques from 12 macropods was determined. The major group of organisms was gram-positive filamentous and pleomorphic rods whose median representation was 92.2%. These were mainly Actinomyces viscosus (median value 62.5%) and Bacterionema matruchotii (median value 23.2%). Streptococci were poorly represented (median value 4.2%) as were anaerobic gram-negative organisms. Aerobic gram-negative bacteria were identified as neisseriae and Moraxella sp. The macropod plaque flora was compared with that of human beings and rodents and the differences discussed in relation to dietary differences and the early externalization of the marsupial young.