As the first and only presenting feature of acute myeloid leukemia (AML), unilateral proptosis in children is uncommon. We report the cases of two girls who had no systemic clinical manifestations of AML. Orbital imaging showed space-occupying infiltrating lesions without surrounding bone erosion. Incisional biopsy and immunohistochemistry were diagnostic for myeloid sarcoma. Systemic workup and bone marrow examination showed features of AML. Systemic chemotherapy was administered to both children, who responded well to the treatment. Myeloid sarcoma should be kept in the differentials of the children presenting with isolated proptosis. Immunohistochemistry may provide an accurate diagnosis and early treatment may lead to a prompt recovery with a good prognosis.