Two treatments to effect low-oxygen conditions for chilled storage of lamb carcasses were compared. Carcasses were placed in bags of low gas permeability and either flushed with nitrogen or filled with carbon dioxide. Carbon dioxide significantly reduced, the growth of gram-negative oxidative and fermentative bacteria, Brochofhrix thermosphacta, and lactic-acid bacteria both on surface tissues and in the purge fluid (weep) from the carcasses. The mean pH of the purge fluid from both sets of carcasses was 6.3. When primal cuts prepared from stored carcasses were held in air at 5°C, development of off-odors was slower for the carcasses that had been stored in carbon dioxide. While the aerobic spoilage flora of loins from unstored carcasses was composed mainly of B.thermosphacta and oxidative gram-negative bacteria, this latter group became a smaller component of the spoilage flora of the loins the longer the carcasses had been stored.