Cytogenetic changes are important for the pathophysiology, risk stratification, treatment and prognosis of the myeloid and lymphoid malignancies. The t(1;19) abnormality which is generally observed in childhood acute lymphoblastic leukemia is rarely found in adult myeloid malignancies. Here, we present a case of acute myeloid leukemia (AML) transformed from myelodisplastic syndrome (MDS), which relapsed with t(1;19) chromosomal abnormality after allogenic transplantation. Sixty-one years old male patient did not response the classical 7+3 induction treatment of AML. The disease went into remission after reinduction treatment, however, relapsed four months later. Allogenic transplantation was performed. Despite the posttransplant remission, the disease relapsed after eight months and cytogenetic analysis of the bone morrow biopsy revealed t(1;19). Second allogenic transplantation was planned, but the disease did not response to salvage chemotherapy. After partial remission provided by desitabin and 5-azasitidin treatments, second allogenic transplantation was performed. Cytogenetic analysis of posttransplant bone marrow biopsy did not show t(1;19) abnormality. However, the disease relapsed two months later with t(1;19). Patient died five months after second transplantation. In this case, which has t(1;19) abnormality at relapse after allogenic transplantation and unresponsive the multiple treatment lines, t(1;19) abnormality can be associated with poor prognosis.