For food evaluation, the determination of the number of Staphylococcus aureus colonies is insufficient in the view of present scientific knowledge. The results, advantages and disadvantages of diagnostic methods are demonstrated on an example of three methods of detection of staphylococcal enterotoxins in milk and milk products. 133 strains were investigated with the method of biotyping of Staphylococcus aureus strains. Four of their strains were included in biotype A, seven strains of S. aureus were not included in any biotype and the other strains belonged in biotypes C and E. This method can be used as an auxiliary method for evaluation of foods containing S. aureus bacteria. The agar-gel precipitation method of enterotoxin detection in isolated strains of Staphylococcus aureus has just restricted valiability. When examining 96 strains of S. aureus with this method, strains which were producing staphylococcal enterotoxins were isolated 17 times. The main disadvantage of this method is a fact that the result concerning the isolated strains need not be identical with the result of enterotoxin detection in food. Direct assays of staphylococcal enterotoxins in milk and milk products using an enzymoimmunological method (ELISA test) seem to be most promising, mainly due to their high sensitivity (0.0001-0.001 micrograms.ml-1) and other advantages.