Philadelphia chromosome-positive (Ph+) T-cell acute lymphoblastic leukemia (T-ALL) is a rare and aggressive type of acute leukemia. The Philadelphia chromosome is the hallmark of chronic myeloid leukemia (CML). The differentiation between Ph+ T-ALL and T-cell lymphoblastic crisis of CML may be problematic in some cases. Here, we report a rare case of de novo Ph+ T-ALL that presented a diagnostic challenge. The overall clinical, immunophenotypic, cytogenetic, and xenotransplantation results suggest a diagnosis of Ph+ T-ALL. The patient was treated with induction chemotherapy including imatinib followed by haploidentical stem cell transplantation and achieved complete remission.