The present invention demonstrates that the diagnosis and prediction of clinical behavior in patients with hematologic malignancies, such as leukemia, can be accomplished by analysis of proteins present in a plasma sample. Thus, in particular embodiments the present invention uses plasma to create a diagnostic or prognostic protein profile of a hematologic malignancy comprising collecting plasma samples from a population of patients with hematologic malignancies; generating protein spectra from the plasma samples with or without fractionation; comparing the protein spectra with clinical data; and identifying protein markers in the plasma samples that correlate with the clinical data. Protein markers identified by this approach can then be used to create a protein profile that can be used to diagnose the hematologic malignancy or determine the prognosis of the hematologic malignancy. Potentially these specific proteins can be identified and targeted in the therapy of these malignancies.