The bacteria within open and closed comedones were evaluated quantitatively and the cocci classified by the Baird-Parker scheme. Corynebacterium acnes and gram positive cocci were always present. The anaerobes greatly outnumbered the aerobes in both types. C acnes was more numerous in closed comedones. Staphylococcus type II (SII) was the predominant member of the coccal flora. Micrococcus isolates were rare.