Thirty-six cases of acute myeloid leukaemia (AML) were tested with a large battery of monoclonal antibodies (moAbs) detecting surface markers normally expressed by myelomonocytic, T and B lymphoid, megakaryocytic and erythroid lineages. Differences in antigenic expression were observed among the various FAB subgroups: HLA-class II molecules were found in almost all AML cases but not in the promyelocytic subgroup (M3); CD14 and CD36 antigens were detected in monocytic leukaemias (M4 and M5); the CD34 moAb (MY10) recognizing an epitope described on myeloid stem cells was positive in 88% of the M1 and 80% of the M3 cases. By a multivariate analysis, only the CD14b (MY4) discriminated significantly between M1-M2 and M4-M5 subgroups. Using Cox's model to assess the prognostic importance of variables including immunophenotyping on survival, we undertook a one by one analysis and found that the presence of CD17 antigen predicted for a shorter survival (P = 0.03). In addition this marker appeared more significant than other clinical and biological parameters.