In neoplastic patients chemotherapy frequently involves severe myeloid suppression. Sometimes myeloid suppression is the main cause of therapy recycling delay with severe and prolonged neutropenia, anaemia and thrombocytopenia. Our study aimed to verify whether there is a correlation between reticulocyte fractions, reticulocyte indices, myeloperoxidase index (MPXI) and post-chemotherapy myelopoietic function and severe post-chemotherapy neutropenia. A cohort of 112 patients was identified, 30 with lymphoma or myeloma and 82 with solid neoplasms with bone marrow micrometastases. The patients were treated with chemotherapy (CT). After CT, 60 patients had neutropenia (ANC <500/mcl) for a median of 7 days (range 3-21). Before CT, myelopoietic function was assessed by the above-mentioned parameters using a hematologic automated analyzer. We assigned patients with an MPXI-positive value and medium adsorbance fraction of reticulocyte (MFR) >10.7% a score of 1, and a score of 0 was assigned to the remaining patients. Patients with a score of 1 showed a lower number of neutropenic events (only 9 out of 36 patients) than those with a score of 0 (51 out of 76 patients), p<0.0001. MPXI and MFR may be used in the assessment of myelopoiesis before CT administration, independently of the type of tumor, CT regimen and number of CT cycle, with the aim of identifying a patient subset with a lower risk of developing neutropenia post-CT.