Chromosomal aberrations have been reported in most malignant hematopoietic disorders such as acute or chronic myeloid leukemia, acute lymphoid leukemia, and myelodysplastic syndromes. Eosinophilic leukemia is a rare hematologic malignancy difficult to distinguish from other forms of idiopathic hypereosinophilic syndrome, so that the diagnosis is often made by exclusion, unless cytogenetic abnormalities can be demonstrated in bone marrow cells. We describe a patient with eosinophilic leukemia whose cytogenetic study shows a t(2;5)(p23;q31). Initial data could suggest a clonal eosinophilia, with an hepatosplenomegaly, severe pancytopenia, and a high level of blood and medullar eosinophilia.