The microbial community in the gut of phylogenetically lower termites, comprising both flagellated protists and prokaryotes, has fascinated many scientists because of the symbiotic relationships that are responsible for the efficient degradation of lignocellulose. However, the complex nature of this microbial community and the formidable unculturability of most members have hampered detailed microbial studies. Comprehensive phylogenetic descriptions of the community members in the past decade still provide little information about their functions because the community contains diverse novel microbial species. Recent advances in molecular approaches have shed new light on species-specific spatial distributions, particularly the cellular associations of flagellated protists and prokaryotes, their functional interactions and coevolutionary relationships. These advances have gradually unveiled how this symbiotic complex functions to efficiently utilize lignocellulose.