Purpose Multiple myeloma (MM) is a haematological malignancy that affects plasma cells in the bone marrow. Recently, [ 18 F]fludarabine has been introduced as an innovative PET radiotracer for imaging lymphoma. It demonstrated a great potential for accurate imaging of lymphopro-liferative disorders. With the goal to question the usefulness of [ 18 F]fludarabine-PET in other haematological diseases, an in vivo MM model was investigated. Methods RPMI8226-GFP-Luc MM cells expressing the green fluorescent protein (GFP) as well as the luciferase reporter (Luc) were derived from the parental RPMI8226 cells. They were injected subcutaneously into the flank of nude mice. Myeloma tumour growth was followed using bioluminescence-based imaging (BLI) and characterised by immunohistochemistry (IHC). The tumour specificity of [ 18 F]fludarabine was evaluated and compared to [ 18 F]FDG. Results The tumoural uptake of [ 18 F]FDG was greater than that of [ 18 F]fludarabine. However, the quantitative data extracted from IHC stainings were in better agreement with [ 18 F]fludara-bine, when compared to [ 18 F]FDG. The relationship between the tumoural uptake of [ 18 F]-labelled tracers and the BLI quantitative data was also in favour of [ 18 F]fludarabine.