Summary A new procedure for determining cleanliness of milk processing equipment is discussed. Calcium was removed from milk-contact surfaces by applications of 1 M HC1 and scraping with a plastic spatula. Quantities removed were determined by atomic absorption spectroscopy. The mean residual concentration of calcium on equipment after “control cleaning” was equivalent to 0.07 mg/100 cm 2 , and 95% confidence limits indicated insufficient cleaning if the residual was 0.08 mg/100 cm 2 or higher. Suggestions for improving the method are included.