monosomy 8; 3 (25%) patients did not have metaphases and 3 (25%) had a normal karyotype. PCR analyses was done in one Ph+ and one Ph patient, and showed in both BCR/ABL rearrangement with p190 expression. One of bilineal leukemias showed trisomy 4, and other del(8)q(22). Five (42%) patients received lymphoid-like therapy: one obtained CR and still surviving; one relapsed after 3 months and died of disease progression; two were resistant but still surviving and one obtained CR with second line treatment and MUD PBSCT and still surviving (6 years) Seven (58%) patients received myeloid like therapy: 4 (33%) died after induction therapy; 3 (25%) were resistant and died of disease progression. The overall median survival was 5 months, with 4 (33%) still surviving with a median follow up of 31 months. One patient with bilineal leukemia received myeloid-like therapy and died after induction therapy; second received high dose therapy for AML followed by BMT, obtained CR and still surviving (7 years). Conclusion: Our results confirm a severe prognosis of biphenotypic and bilineal acute leukemias, especially after myeloid-like treatments. Although there are no uniform criteria about whether to treat these patients, intensive approach with high dose therapy followed by bone marrow transplantation, will be required to eradicate the disease.