1. Sampling carcasses after plucking or after the post-evisceration spray-wash showed that 10 or 20 ppm available chlorine in the processing-plant water supply caused little reduction in carcass contamination. 2. When 20 ppm chlorine was used in the water supply to parts of the processing-plant other than the mechanical immersion chilling system, counts of faecal and spoilage bacteria from carcasses were reduced approximately 10-fold after passage through the chilling system; bacterial carry-over of chlorine from the final spray-washer. 3. Artificial contamination of carcasses with a readily identifiable strain of Escherichia coli confirmed the occurrence of cross-contamination during plucking and evisceration; in-plant chlorination reduced neither the proportion of carasses contaminated nor the numbers of organisms transferred at these stages. 4. In most cases the chlorine-resistance of poultry spoilage pseudomonads was greater than that of E. coli; hence in-plant chlorination is to be recommended for processing-plant water supplies which carry such spoilage organisms.