The surface of the trypanosomatid forms the interface between the parasite and its host, and has evolved to repel a variety of host anti-microbial defences. The flagellar pocket constitutes a highly differentiated region of the trypanosomatid surface that facilitates internalization of host macromolecules, while restricting host access to the exposed, endocytic receptors of the parasite. In this review, Paul Webster and David Russell discuss the ability of this organelle to accumulate efficiently nutrients obtained from the host as a major factor in the success of this group of parasites.