Development of faecal bacteria composition of calf fed on milk or a combined diet was investigated. Bacteria were enumerated by cultivation in calves aged from 4 to 2l days. In day-old calves bifidobacteria levels in both groups were very similar. In 7 day-old calves an influence of diet composition on faecal bacteria was observed. Bifidobacteria in milk-fed calves increased and did not change to the end of the study. In calves fed the combined diet bifidobacteria also increased, but slowly and reachingcounts similar as lactobacilli, coliforms and enterococci. Milk-fed calves had nonsignificantly higher counts of total anaerobes and coliforms compare to calves on combined diet. Lactobacilli and enterococci were more numerous in calves on the combineddiet. Our results showed that the occurrence of bifidobacteria in calf faeces is highly dependent on the diet composition.