Long-term in vitro cultures of blood-stage parasites are so far feasible only for Plasmodium falciparum and P. knowlesi . In this chapter, we describe short-term ex vivo culturing of P. cynomolgi and P. vivax . We also describe long-term in vitro culturing of P. knowlesi as well as some techniques for synchronizing parasites. Cultured parasites can be used for a variety of purposes, e.g., for in vitro drug assays and antibody-mediated growth inhibition assays.