Multidrug resistance (MDR) is one of the major problems affecting the treatment of cancer. In vivo visualization and quantification of MDR proteins would be of great value to better select the therapeutic strategy. Six flavone-based compounds were synthesized and evaluated for their cytotoxic activity and MDR-reversing capacity using hMRP1 or hMDR1 overexpressing cell lines for in vitro assays. All the flavone derivatives were highly selective for hMRP1-expressing cell lines. These derivatives each used at 4muM (a non-cytotoxic concentration) enhance significantly the sensitivity of hMRP1-mediated MDR cell line toward doxorubicin toxicity. Their MDR-reversing capacity suggests that, in particular, the 4'-fluoroalkyloxy and 4'-iodo apigenin derivatives are potential new radiopharmaceuticals to visualize in vivo MRP1-mediated MDR phenomenon by PET or SPECT.