Two cases of myeloid leukemias (acute [AML M2] and chronic [CMC]), blastic crisis, with identical t(2;3)(p13;q26) are described. These cases had some peculiarities: no significant decrease of blood thrombocyte count in the AML patient and high increase of blood thrombocyte count during blastic phase in the CML patient; dysplastic megakaryocytes in bone marrow and unfavorable course of the disease; and short remission (3 months) in AML and short chronic phase (8 months) in CML. Clinical and morphologic findings in patients with t(2;3)(p13;q26) resembled those in cases with 3q21q26 syndrome or with other chromosome rearrangements involving 3q21 or 3q26.