Eosinophils are usually considered as an end-stage cell, involved only in host protection against parasites or allergic diseases. However, there is accumulating evidence showing that eosinophils are multifunctional leukocytes involved in several immunological responses. In this report, a patient with persistent eosinophilia, who was finally diagnosed as prostatic adenocarcinoma, is presented and discussed. While any tumor can induce eosinophilia, prostate carcinoma-related eosinophilia is quite rare, according to the current medical literature. Moreover, some remarkable findings about eosinophils and prostate tumor cells, other than the recently reported ordinary `eosinophil-tumor cell` interactions, are also highlighted.