Polymeric vesicles, or polymersomes, are nano- to micrometre sized polymeric capsules with a bilayered membrane. Applications of these vesicles are foreseen in nanomedicine, in vivo imaging and drug delivery. These applications put many restrictions on the choice of polymer, the size and the surface of the vesicle. In this respect much can be learned and translated to polymersome science from lines of research with a longer history of practical knowledge such as liposomal formulation and polymer drug conjugation. The dimensions of a vesicle, such as size and shape can be controlled for polymersomes and will influence the in vivo circulation time. The surface can be adjusted to induce stealth character, or chemically modified to introduce targeting moieties. And last but not least the choice of block copolymers - the building blocks of a polymersome - can introduce features like biocompatibility, inherent or induced permeability and triggered release. In this review we will discuss the recent advances in polymersome science with regard to biomedical applications and will specifically address the abovementioned features which affect their biological behaviour.