FB2 is a novel Abl/Src dual tyrosine kinase inhibitor which is designed to overcome imatinib resistance. Besides imatinib-sensitive cell lines (K562), FB2 significantly inhibited the growth of imatinib-resistant cell lines of different resistance mechanisms (K562/G5.0 and K562/G01), and decreased the expression of autophosphorylation of Bcr/Abl, c-Src and Lyn kinases on them. It also inhibited the proliferation of Src over activated cells DU145 and MDA-MB-231. Furthermore, FB2 potently prolonged the survival time of non-obese diabetic/severe combined immunodeficient mice harboured K562/G5.0 cells. These results indicated that FB2, an Abl/Src dual tyrosine kinase inhibitor, is a promising candidate for imatinib-resistant CML and Src over activated cancer.