Staphylococcal enterotoxins (SEs) are big heterogenic group of exotoxins, rather differential in respect of their nucleotide and amino-acid homology, as well as the location of their genes, molecular weight and iso-electric point value. SEs were identified in 1959 as the extra-cellular proteins produced by some Staphylococcus aureus strains. These enterotoxins are known as the pyrogenic toxins and this group contains also other staphylococcal toxins (staphylococcal toxic-shock syndrome toxin--TSST-1, A and B exfoliative toxins and streptococcal scarlet fever toxin). Twenty one serological types of staphylococcal enterotoxins are distinguished. All of them are structurally and functionally similar to the toxic shock syndrome toxin (TSST-1). SEs are thermo-stabile proteins, resistant to many proteolytic enzymes (pepsin, trypsine, chymotrypsine, renine and papain), but this resistance depends on the temperature and pH. Staphylococcal enterotoxin-encoding genes are located as well in the chromosomal DNA, as on the pathogenicity island, in phages, transposones and plasmids. Enterotoxins are staphylococcal virulence factors responsible for food poisonings in humans. These proteins are also isolated from cows with mastitis. In various countries, the percentage of enterotoxin-producing S. aureus strains ranges from 5 to 60%, depending on the enterotoxine type. The variability and prevalence of enterotoxins produced by staphylococci isolated from mastitic cows is very important clinical and epidemiological problem. The analysis of enterotoxins interrelations, their structure, properties and occurrence, will provide better revealing their role in the emerging, development and spreading of human and animal diseases. Classical enterotoxins, as well as the new types of these proteins, are variable element of staphylococcal virulence that connects the occurence of mastitis with human food poisonings.