Whole-body fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) has been useful in the management of a variety of malignancies. In patients with chemotherapy followed by bone marrow stimulants such as granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor, the bone marrow will have diffuse, increased FDG accumulation. Therefore, diffuse bone marrow FDG uptake is commonly attributable to the effect of hematopoietic cytokines. However, diffuse bone marrow FDG uptake can also be caused by bone marrow involvement by malignancy. The authors report a patient with diffuse bone marrow involvement of Hodgkin disease that appears indistinguishable from hematopoietic cytokine-mediated FDG bone marrow uptake.