The treatment outcome and development of new mutations in patients with imatinib- and/or nilotinib-failure Philadelphia chromosome positive (Ph+) leukemia with highly nilotinib-resistant mutations (Y253H, E255K/V and F359V/C) were assessed on dasatinib therapy. A total of 111 patients with Ph+ leukemia were grouped into three cohorts by baseline BCR-ABL kinase domain mutation status: no mutation (n = 44), non-nilotinib-resistant mutations (n = 26) or nilotinib-resistant mutations (n = 41). The frequencies of hematological, cytogenetic and molecular responses and clinical resistance to dasatinib were similar among the three cohorts during dasatinib therapy. In dasatinib-resistant patients, new mutations were most frequently observed in the cohort with nilotinib-resistant mutations (p = 0.001). Multivariate analysis revealed that advanced disease and harboring Y253H or F359V mutation before dasatinib were independent predictors of developing new mutations. We conclude that patients with Ph+ leukemia with Y253H or F359V mutation have a high likelihood of developing new mutations in the setting of dasatinib resistance.