The effect of Bacillus cereus var. toyoi spores and avilamycin as bacterial and antibiotic growth promoters, respectively, on faecal microflora of turkeys was determined. The experiment was carried out on 108 turkeys randomly allocated to 3 groups: control and avilamycin- or Bacillus spore-treated. After 12 weeks of feed supplementation and a subsequent 4-week period following withdrawal, selected groups of faecal microflora were determined, and the results were compared with those in the control group. Neither avilamycin nor B. cereus var. toyoi spores affected Bifidobacterium or Lactobacillus counts, whereas both supplements significantly increased the counts of E. coli by 0.84 and 0.69 log cycle (P ≤ 0.05 for both). B. cereus var. toyoi caused a significant increase in counts of spores of both aerobic and anaerobic proteolytic bacteria by 0.98 (P ≤ 0.001) and 0.83 (P ≤ 0.01) log cycle, respectively. At the end of the period following withdrawal, in the avilamycin group, counts of Bifidobacterium and Lactobacillus significantly decreased by 1.14 (P ≤ 0.01) and 1.97 (P ≤ 0.001) log cycle, respectively, as did the counts of anaerobic proteolytic bacteria spores, which decreased by 1.18 (P ≤ 0.001). In the B. cereus var. toyoi group, however, increased counts of Lactobacillus, by 0.91 (P≤0.01), E. coli, by 0.71 (P ≤ 0.05), anaerobic proteolytic bacteria spores, by 1.37 (P ≤ 0.001), and of anaerobic saccharolytic bacteria spores, by 0.72 (P ≤ 0.05) log cycle were found. The tested growth promoters did not affect the groups of beneficial gut microflora, whereas they stimulated the growth of opportunistic bacteria. The performance parameters of turkeys, better in groups administered avilamycin and B. cereus var. toyoi, were comparable with the control at the end of period after withdrawal.