Leishmania have long been known to clinicians and parasitologists as the causative agents of a variety of acute or chronic, cutaneous or visceral diseases in mammalian hosts. More recently, these protozoan parasites have evoked the interest of immunologists, as Leishmania infections are an excellent model for studying T-cell dominated antiparasite immune responses. In this review, Christian Bogdan, Martin Röllinghoff and Werner Solbach discuss the multiple interactions of Leishmania with components of the host immune system that illustrate the variety of highly elaborate evasion strategies developed by this parasite. © 1990.