We present a 61-year-old man with marked peripheral blood eosinophilia, feature of hypereosinophilic syndrome, that later evolved into acute lymphocytic leukemia (ALL-L2). Initially the patient suffered from significant complications related to eosinophilic toxicity, including large urticarial hyperpigmented plaques, myocardial infarction, and eosinophilic pneumonia. He was treated with high dose of steroids resulting in a rapid suppression of the eosinophilia. Two weeks later, the eosinophilia had relapsed, so a bone marrow aspiration was performed. Cytomorphological examination of the bone marrow showed typical ALL features, while flow cytometric analysis revealed an My+pre-B-ALL immunophenotype, and chromosome analysis of bone marrow showed a normal karyotype. He received chemotherapy according to the standard protocol for ALL and died from refractory respiratory failure and congestive heart failure immediately after antileukemic therapy. We review the literature and compare the demographics, clinical features, and outcomes of several cases and reported studies.