Eighty half carcasses were either: (a) hand-washed with tap water (15 C) or (b) washed (15 C) with an experimental beef carcass cleaning unit. Overall logarithmic mean reduction in aerobic plate counts were 0.99 for hand-washed carcasses and 1.07 for those machine-washed. No significant difference (P ⩽ 0.05) was noted in percentage dirt and smear reductions due to type of wash (hand or machine). However, 12.5% of the hand-washed carcasses and 22.5% of the machine-washed carcasses contained defects caused by hair. The authors concluded that the machine was at least as effective as the careful hand washing in this experiment.