The psychrotrotrophic flora of chicken carcases in 3 different industrial processing plants has been studied. The micro‐organisms, 5920 strains, were placed in 4 categories (arranged in decreasing order of the number of isolates): (1), Pseudomonas and Achromobacter (Acineto‐bacter); (2) Flavobacterium, Corynebacterium and yeasts; (3), Aeromonas and Entero‐bacteriaceae; (4), lactic acid bacteria, Micrococcaceae and Bacillus. Different types of strains belonging to these groups are described and the importance of each is discussed with reference to the observations of other authors. The proteolytic action of 1717 of the 5920 isolates was studied.