Increased cholesterol levels are being increasingly recognised as risk factors for the onset and progression of several cancers. Now researchers in Portugal show that high levels of cholesterol can affect the microenvironment of the bone marrow, so that more cells move from the bone marrow to peripheral, circulating blood. These findings, by Sergio Dias and his team, an external group of the Instituto Gulbenkian de Ciência, have implications for transplantation and further understanding bone marrow malignancies, are to appear in the next issue of the journal Blood.