Dasatinib is effective second line treatment for patients with chronic myeloid leukemia (CML) resistant or intolerant to imatinib. We report here the first experiences with dasatinib therapy in 71 CML patients resistant or intolerant to imatinib from the real clinical practice of 6 hematological centers in the Czech Republic. Dose 100 mg daily and 70 mg twice daily was administered to patients with chronic phase (CP) and advanced phases (AP) CML. In chronic phase (n=46), complete hematological reponse (CHR) was achieved in 97%, major cytogenetic reponse (MCgR) in 77% and complete cytogenetic response (CCgR) in 67%. Major molecular reponse (MMR) was achieved in 19/31 patients in median of 10 months. In advanced phase (n=25), CHR was attained in 77%, MCgR in 39%, CCgR in 33% and MMR in 2/18 patients. Eleven different baseline mutations were followed up in 15 patients. Dasatinib eliminated mutations in most of the patients, but 3 patients acquired a new one. Novel mutations were detected under dasatinib therapy in 2 patients. Dasatinib was well tolerated, cytopenias were common and was managed by dose modification. The estimated progression free survival (PFS) at 12 months was 97+/-3% in CP and 62+/-21% in AP. The median time to treatment failure was 605 days in AP while it was not reached in CP patients. Our clinical experiences, described here, confirmed that dasatinib is associated with high response rates especially in imatinib resistant or intolerant CML patients in chronic phase.