Tissue eosinophilia was observed in the subcutaneous tissue of mice shortly after their inoculation not only with living but also with lysed promastigotes of Leishmania amazonensis. Intraperitoneal inoculation of lysed promastigotes from five different Leishmania species (L. donovani, L. chagasi, L. tropica, L. amazonensis, and L. braziliensis) induced eosinophil accumulation in the mouse peritoneum. This eosinophil infiltration was also detected in C5-deficient AKR mice, indicating complement independent eosinophil chemotaxis by the parasite. The induced eosinophils were hypodense, suggesting activation of the cells. Finally, we demonstrated in vitro eosinophil chemotactic activity in the promastigote lysates using purified eosinophils and blind well chambers. These results suggest the presence of an eosinophil chemotactic factor in Leishmania, a protozoan parasite.