In order to investigate the prognostic value of immunologic markers together with the most relevant clinical and hematological disease characteristics in acute myeloblastic leukemia (AML), the reactivity of blast cells from 102 patients with AML was analyzed with a panel of twenty monoclonal antibodies. The univariate analysis showed that five parameters had an adverse effect on both complete remission (CR) and survival: advanced age (greater than 60 years), anemia (hemoglobin concentration (Hb) less than 10g/dl), the expression of the antigens detected by the anti-megakaryocytic antibodies (CDw41/CDw42), the monocytic antibodies (CD14), and the CD9 (FMC56, FMC8) antigen. In addition, the failure to obtain CR had a significant adverse effect on survival (p less than 0.0001). Multivariate analysis showed that only age and Hb had a significant influence on CR while for predicting survival the most important independent prognostic factors were: CR, age, number of platelets and reactivity with the CD9 antibody. These results show that immunological markers could represent a valuable tool in the assignment of risk categories in AML patients.