overexpression of BCRP in certain tumor cell lines causes cross‐resistance against various drugs used in chemotherapeutic treatment. In a previous work we showed that a new class of compounds derived from XR9576 (tariquidar) selectivelyinhibitsBCRP. In this work we synthesized more members of this class, with modification on the second and third aromatic rings. The inhibitory activities against BCRP and P‐gp