Of a total of 119 strains of bacteria from 3 depths in an acid peat on Signy Island, S. Orkney, 52% belonged to the genus Brevibacterium. Twelve other genera were recorded of which numerically the most important were Arthrobacter, Cellulomonas, Kurthia and Micrococcus. 62% of the collection were psychrophilic, but only 4 strains were obligate psychrophiles. No pattern could be established for the various genera from different depths. The fine structure of an obligately psychrophilic pleomorphic rod from the peat is illustrated and discussed.