One of the most complex microbial ecosystems is represented by the microbiota of the human gastrointestinal tract (GIT). Although this microbial consortium has been recognized to have a crucial effect on human health, its precise composition is still not fully established. Among the GIT bacteria, bifidobacteria represent an important commensal group whose presence is often associated with health-promoting effects. In this work, we assessed the complexity of the human intestinal bifidobacterial population by analysing the diversity of several 16S rRNA gene-based libraries. These analyses showed the presence of novel bifidobacterial phylotypes, which had not been found earlier and may thus represent novel taxa within the genus Bifidobacterium.