Bifidobacteria and other bacterial groups (lactobacilli, facultative anaerobes, anaerobes) from the digestive tract of three bumblebee species were enumerated and characterized. Bifidobacteria were found in 42 out of 61 specimens. Twenty-three specimens had counts of bifidobacteria higher than 7.0 log CFU/g. Bifidobacteria represented the dominant group of anaerobes (> 70% of total anaerobes) in the digestive tract. For the first time, bifidobacteria were isolated from the digestive tract of bumblebees. We suggest on the basis of biochemical tests and genetic methods (PCR and DGGE) that these bacteria may represent new species within the family of Bifidobacteriaceae.