Parasites interact with different B cell compartments triggering, in most cases, a vigorous antibody response. Unfortunately, this response is not necessarily protective; indeed, it can be harmful for the host. In this chapter we describe how protozoan parasites and helminths induce mature B cell responses and how B cells influence the characteristics of T cell response involved in parasite control. To protect themselves, the parasites develop unique ways to evade B cell responses, including changes in their antigenic coat and induction of immunosuppression and apoptosis of B cells. We discuss how parasites elude B cell immunity establishing a favourable balance that drives the infection to chronicity.