Peripheral eosinophilia is a rare but recognized accompaniment of malignant disease. Two unusual cases, one with a histiocytic lymphoma and the other with cervical carcinoma, are described. In the first patient, pulmonary infiltrates developed at the height of the eosinophilia and in the second, the peripheral eosinophilia heralded the onset of disseminated disease. Tumor-associated peripheral eosinophilia is reviewed, and it is concluded that peripheral eosinophilia associated with a malignant setting is a marker of extensive disease and is thus associated with a poor prognosis.