Dasatinib, a tyrosine kinase inhibitor, is usually prescribed for chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. However, some patients may develop an intolerance to this drug over the years. Among various toxicities related to dasatinib, dasatinib-associated interstitial pneumonitis is not reported frequently in the literature yet. Moreover, published studies have reported only few cases of dasatinib-associated pneumonitis, almost exclusively in chronic myeloid leukemia. In this study, we describe three cases of dasatinib-associated interstitial pneumonitis in patients with chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia (a 56-year-old man, a 34-year-old man, and a 46-year-old woman) at our institution. In all three patients, the time from the initiation of dasatinib therapy to the onset of interstitial pneumonitis varied greatly. Among them, one patient underwent a surgical lung biopsy, which revealed chronic granulomatous inflammation without any causative pathogen. In all patients, dasatinib was discontinued after the diagnosis of interstitial pneumonitis, and two patients were treated with systemic steroids. Although infrequent, dasatinib-induced pneumonitis should be considered a possible diagnosis in dasatinib-treated patients with fever and respiratory symptoms. In addition, hematologists and pulmonologists should be aware of this rare but critical toxicity.