Abstract: Ewing sarcoma (EWS) is an invasive and primary bone tumor with a high incidence in children and adolescents. The presence and extent of metastases at the time of diagnosis remains the most important prognostic factor in determining a patient’s prognosis. Up now, considerable ambiguity exists regarding the optimal modality for detecting bone marrow metastases. Bone marrow biopsy and/or aspiration (BMBA) is the gold standard for determining bone marrow metastases. This invasive and painful procedure may be amenable to being replaced by ¹⁸F-FDG PET/CT because of its high sensitivity in detecting EWS bone and extraosseous metastases. This review provides an overview of the current literature, concludes that there is no longer a systematic consensus on the implementation of BMAB criteria for the diagnosis of bone marrow metastases in EWS, and summarizes the current practical strategies and clinical practices for the diagnosis of EWS bone marrow metastases accordingly.