The epidemiological situation connected with S. enteritidis in Poland, in the years 1961-1991, is described. During this period there were two increases in infections and food poisonings, which were of an epidemiological character. The first epidemic, in 1962-1976, affected primarily small children and spread by contact in a hospital environment. It caused serious diseases, or dangerous complications in already existing illnesses, with high mortality. A few foci of later food poisonings were caused by infected meat or meat by-products. The second epidemic, which began in 1980 or 1981 and still exists, has already affected about 500 000 persons. It has often concerned cases of sporadic infections, mainly in the case of small children, but it has not been of a hospital epidemic character. It has been far more frequently associated with food poisoning outbreaks caused by contaminated ice-cream, cream cakes, eggs, mayonnaise and, less frequently, by meat and meat by-products. Attention is drawn to the large number of humans transmitting S. enteritidis infections in Poland.