The effects of solutions of 0.02% peroxyacetic acid, acidified 0.16% sodium chlorite, 2% lactic acid and 4% lactic acid on the natural flora of the distal surfaces of pieces of brisket, from chilled beef carcass quarters delivered from two slaughtering plants to a processing plant, were investigated. Peroxyacetic acid and acidified sodium chlorite solutions had little effect on the numbers of aerobes, coliforms or Escherichia coli on meat from one plant, and were less effective than 4% lactic acid for reducing the numbers of bacteria on meat from the other plant. With meat from both plants, treatment of meat with 4% lactic acid and holding for 5 or 60 min at 7+/-1 degrees C before sampling resulted in reductions of all three groups of bacteria by >/=1.5 log unit. Treatment with 2% lactic acid resulted in similar reductions when meat was sampled 5 min after the treatment, but reductions were about 1 log unit when meat was sampled 60 min after the treatment. Treatment of carcass quarters with 4% lactic acid resulted in reductions of bacterial numbers of >/=2 log units at distal surfaces, but </=2 log units at medial surfaces. The findings indicate that the efficacies of antimicrobial solutions may be inconsistent when they are applied to chilled meat from different sources and to different types of meat surface, and that bacteria injured by application of an antimicrobial solution may recover during processing of meat at temperatures about 7 degrees C. However, 4% lactic acid may be generally useful as a decontaminant for chilled, raw meat.