Dasatinib, a second-generation tyrosine kinase inhibitor, is used for treating patients with Philadelphia chromosome (Ph) positive leukemia, especially for those who are resistant or intolerant to imatinib. The common adverse effects associated to its use include myelosuppression, nausea, diarrhea, and peripheral edema. This study reports a very rare case of a 60-year-old male who suffered from severe thrombocytopenia after dasatinib administration. The platelet count did not increase even after dasatinib had been discontinued for more than 6 months. Various means had been tried, but the count of platelet did not increase, and the result was not optimistic. This is the first report of so severe thrombocytopenia after dasatinib treatment, and the pathophysiology underlying this reaction remains unknown. We hope that this case will help remind clinicians to pay more attention to the side effect of thrombocytopenia caused by dasatinib in the future.