Northern blot analysis was used to assess the level of expression of five protooncogenes and histone H3 in the bone marrow cells of patients with acute nonlymphocytic leukemia (ANLL). The relationship between the level of gene expression and the clinical characteristics of the disease and response to therapy was studied. The levels of expression of c-myc and c-myb are weakly correlated and are unrelated to French- American-British (FAB) type of ANLL. The levels of expression of c-fms, c-fes, and c-fos are highly correlated with each other and are highest in leukemia with a monocytic component (c-fms v FAB = .71, c-fes v FAB = .75). High levels of c-myc expression are associated with a high probability of not responding to remission induction therapy (P = .004). The converse is true for c-fms expression levels. High levels of expression of c-myc or c-myb are associated with short remissions (P = .059 and .065, respectively), perhaps because they are associated with a high capacity for leukemic cell self-renewal and/or an inability of leukemic cells to differentiate in response to chemotherapy.