Diffuse uptake of F-18 fluorodeoxyglucose (FDG) by the whole skeleton has been described in case of bone marrow stimulation resulting from treatment with colony-stimulating factors (CSFs): granulocyte CSF or granulocyte-macrophage CSF. The authors describe such an aspect of diffuse FDG uptake by the bone marrow during the follow-up of rectal cancer in a patient with anemia and recently treated thrice weekly by erythropoietin. To their knowledge, such an aspect of diffuse FDG uptake by the skeleton, revealing the bone marrow stimulation by erythropoietin, has not yet been reported.