Abstract. The aim of the study was to evaluate the effect from supplementation of the prebiotic Immunobeta and the probiotic Zoovit on haematological parameters in Ile-de-France lambs. The experiment was conducted in the experimental farm of the Agricultural Institute, Stara Zagora. A total of 45 lambs divided into 3 groups of 15 animals each with similar initial live body weight, sex and birth type were included – one control and two experimental. Each animal from experimental group I was supplemented once daily with 8 g prebiotic Immunobeta and those from experimental group II received the same amount of the prebiotic plus 4 g probiotic Zoovit. Blood samples for analysis were collected from 8 animals per group in the beginning and the end of the trial. The group supplemented with the combination Immunobeta + Zoovit had statistically significantly higher haemoglobin content (P<0.05) and haematocrit (P=0.013) that the group fed a diet with Immunobeta prebiotic. The mean corpuscular volume was lower (P<0.05) in experimental group I vs. controls. The addition of the Immunobeta prebiotic resulted in reduced haemoglobin (Р=0.012), haematocrit (Р=0.012), mean corpuscular volume (Р<0.001), mean corpuscular haemoglobin concentration (Р<0.001), mean platelet volume (Р=0.002), platelet distribution width (Р=0.001) and volume of platelet participation (Р=0.002) at the end of the trial period. After the supplementation with synbiotic, there was a trend towards lower haemoglobin content (Р=0.088). The Immunobeta + Zoovit addition to the diet resulted in statistically significantly reduced haematocrit (Р<0.05), reduced mean corpuscular volume, mean corpuscular haemoglobin concentration, mean platelet volume (Р<0.001), platelet distribution width (Р<0.01) and volume of platelet participation levels (Р<0.05).