In this issue, a nationwide retrospective Japanese study finds that, in a second opinion setting, one‐third of bone marrow aspirates from patients suspected of myelodysplastic syndromes are heavily haemodiluted. Moreover, in four‐fifths of such cases, the failure to obtain the correct material for diagnosis went undetected by the referring institution. These data are intriguing, but given their special set‐up, caution should be exerted in transposing them to other countries.Commentary on: Ogata et al. Prevalence of massively diluted bone marrow cell samples aspirated from patients with myelodysplastic syndromes (MDS) or suspected MDS: A retrospective analysis of nationwide samples in Japan. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19447.