<p>Automated hematology analyzers are routinely used to assess blood cell counts and leukocyte differentials. However, the accuracy of assessing neutrophil percentages with automated hematology analyzers in patients undergoing chemotherapy has not been examined. In this study, the correlation between neutrophil percentages calculated by automated hematology analyzers and those obtained through manual microscopic examinations by laboratory technicians was investigated on the day of chemotherapy initiation in 125 patients receiving CHOP-based chemotherapy for malignant lymphoma. Peripheral blood counts and 5-part leukocyte differential percentages were analyzed using the Sysmex XE-5000 system. An examination of 797 samples from each chemotherapy course showed a favorable correlation between the two methods (Pearson’s r = 0.917). However, this correlation significantly diminished in samples when the bone marrow nucleated cell count was ≤ 50 × 10⁹/L or granulocyte colony-stimulating factors were administered in previous chemotherapy courses (r = 0.881 and 0.886, respectively). Furthermore, a tendency towards a weaker correlation was noted when the percentage of immature neutrophils exceeded 3% (r = 0.894). Nevertheless, in all these conditions, the correlations consistently had coefficients of &gt; 0.8, emphasizing the robustness of the correlation. Our study suggests that neutrophil percentages calculated by automated hematology analyzers on the first day of chemotherapy were strongly correlated with those obtained through microscopic examinations. Measuring neutrophil counts with an automated hematology analyzer is sufficient, even in patients receiving chemotherapy.&#xa0;</p>