The objective of the study was to compare the efficiency of two species of yeast, Yarrowia lipolytica (YL) and Saccharomyces cerevisiae (SC), with or without a probiotic supplement, added to feed for piglets, on the basis of haematological blood indices and the gut microbiota. A total of 360 piglets (the average 27-d-old) were allotted to dietary treatments: 1) the basal control(C) diet, 2) the C diet + probiotic(P) (a mixture of Bacillus licheniformis and Bacillus subtilis), 3) the C diet +3%YL(Y), 4) the C diet +3%YL + probiotic(YP), 5) the C diet +3%SC(S) and 6) the C diet +3%SC + probiotic(SP). The study showed that YL yeast can be used in compound feeds for piglets interchangeably with SC yeast. The effect of YL on haematological blood parameters and the microbes colonizing the gut proved to be more beneficial than the effect of SC yeast. The combined application of YL or SC with a probiotic had a more favourable effect on the gut microbiota than the use of yeast alone. It should be noted, however, that supplementation of the compound feed with YL in combination with a probiotic reduced the multiplication of coliform bacteria and Escherichia coli in the intestinal contents, while the feed containing SC together with a probiotic did not. The dietary study confirmed that YL in combination with a probiotic is highly suitable for feeding piglets.