<b><i>Introduction:</i></b> Adult patients with acute myeloid leukemia (AML) are usually treated with intensive chemotherapy, leading to prolonged bone marrow aplasia. It is usually assumed that a short duration of aplasia could be a surrogate marker of poor therapeutic efficacy in clearing bone marrow blasts, especially in older patients. No studies have evaluated the usefulness of such a surrogate marker in younger AML patients treated with intensive chemotherapy. <b><i>Materials and Methods:</i></b> In the present study, we retrospectively assessed the role of white blood cell (WBC) count nadir and duration of aplasia in 68 patients with AML treated with intensive chemotherapy and potentially candidate to stem cell transplantation. <b><i>Results:</i></b> The median (interquartile range) bone marrow aplasia was 25 days, and the mean WBC count nadir from chemotherapy start was at day +12, whereas the median neutrophil recovery occurred at day +24. No significant differences were found between responders and nonresponders for mean aplasia duration (25 vs. 26 days, <i>p</i> value = 0.76), mean WBC count nadir (12 vs. 12 days, <i>p</i> value = 0.86), and median neutrophil recovery (24 vs. 24, <i>p</i> value = 0.67). <b><i>Discussion:</i></b> The present study evaluated the potential prognostic role of WBC count nadir and duration of aplasia, demonstrating that they are not associated with treatment outcomes in adult patients with AML treated with intensive chemotherapy. Therefore, a short duration of aplasia seems not linked to poor therapeutic efficacy in clearing bone marrow blasts. Our findings, although needing validation in larger and more homogeneous cohorts, may offer helpful clues in the management of aplasia of AML patients.

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