Background: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. Bone pain is an important symptom that can be severe. Eosinophilia without any other abnormal laboratory findings is rare in ALL. Strongyloides stercoralis in ALL causes disseminated fatal disease.Case Presentation: This 9-year-old girl presented with bone pain in lumbar region. Bone pain was the only symptom. The patient didn' t have organomegaly. The BM samples were studied by flow cytometry, which showed pre-B cell ALL. Larva of Strongyloides stercoralis was found in fecal examination. Plain chest x ray showed bilateral para-cardiac infiltration.Strongyloidiasis was treated before starting chemotherapy. After two days treatment with Mebendazol the patient developed cough, dyspnea, respiratory distress and fever. The treatment changed to Ivermectin for 2 days.Chemotherapy started five days after diagnosis of leukemia.Conclusion: The patient complained merely of bone pain in lumbar region without any other signs and symptoms. Peripheral blood smear showed eosinophilia without any other abnormality. Stool examination showed Strongyloides stercoralis larvae. We suggest that all patients diagnosed as ALL in tropical and subtropical regions should be evaluated for parasitic infection especially with Strongyloides stercoralis.