One hundred and fifty-four acute myeloid leukemia patients with trisomy 8 were studied for their clinical and biological characteristics, and treatment outcome. Forty-seven patients presented with trisomy 8 as the sole aberration, 107 with trisomy 8 associated with other cytogenetic abnormalities (13 with favorable, 54 with intermediate, and 40 with unfavorable risk cytogenetics). Overall complete remission (CR) proportion was 48%. Median disease-free survival (DFS) and overall survival (OS) were 7.8 and 8.3 months, respectively. In multivariate analysis, age >or=60 years (P<0.0001) and association with unfavorable karyotype (P=0.03) were of poor prognostic value for CR achievement. Age >or=60 years (P<0.0001) and antecedents of dysmyelopoiesis (P=0.02) were of poor prognostic value for OS. Patients with trisomy 8 alone did not show any difference in terms of outcome as compared with those in whom trisomy 8 was associated to intermediate risk cytogenetics (P=0.0002). Trisomy 8 in addition to favorable karyotype maintained a good clinical outcome, while trisomy 8 in addition to unfavorable cytogenetics showed the worst prognosis.