Background: Acute myeloid leukemia (AML) and hyperleukocytosis are related to an unfavorable prognosis. The impact of hyperleukocytosis on the prognosis of pediatric AML has not been fully explained so far. We aimed to assess the clinical characteristics and prognosis of pediatric AML with hyperleukocytosis, referred to as white blood cell (WBC) count ≥50×10⁹/L. Methods: A total of 307 newly diagnosed non-acute promyelocytic leukemia patients were continuously enrolled at our center from October 2005 to September 2015. 81 patients with initial leukocyte counts ≥50×10⁹/L. The baseline demographic and clinical characteristics of AML patients were compared. Progression-free survival (PFS) and overall survival (OS) were documented. Results: Hyperleukocytosis occurred in 26.38% of AML patients, and FAB M5 subtype (n=41, 50.62%) and FLT3-ITD mutations (n=16, 19.75%) had a high proportion in AML and hyperleukocytosis. Overall mortality was significantly higher in patients with hyperleukocytosis than patients without hyperleukocytosis (50.62% vs. 35.84%, P=.020). Patients with hyperleukocytosis had a lower 10-year PFS and OS rates than those without hyperleukocytosis (44.4%±9.4% vs. 59.7%±5.5%, P=.041; 49.4%±9.4% vs. 64.2%±5.4%, P=.051, respectively). There were similar PFS and OS rates between the subgroups of patients with WBC count 50-100×10⁹/L and WBC count ≥100×10⁹/L (43.8%±13.3% vs. 44.9%±12.3%, P=.507; 46.9%±13.3% vs. 51.0%±12.3%, P=.907, respectively). In all patients with hyperleukocytosis, male and FAB M5 subtype patients had a significantly inferior survival, while CBF-AML had a better survival. Conclusions: A WBC count greater than 50×10⁹/L at onset was a critical predictive adverse factor in pediatric AML.