A specific method has been developed for the extraction and measurement of staphylococcal nuclease in cheese in which Staphylococcus aureus has grown. Ten grams of cheese sample were homogenized with ninety milliliters of pH ten buffer for three minutes. Ammonium sulfate fractionation was used and a forty to eighty percent fraction was collected and concentrated using ultrafilters. The nuclease activity was determined using a toluidine blue deoxyribonucleic acid agar slide method and a spectophotometric method. The DNA agar slide method was used to compare staphylococcal growth with nuclease production in cheese under varying conditions. When Staphylococcus aureus plate counts indicated populations of three to four thousand per milliliter, it was possible to detect nuclease in the cheese sample. A method has also been developed to detect Staphylococcus aureus colonies using DNase agar and toluidine blue, utilizing the heat stability of Staphylococcus aureus nuclease.