We present the management of a 15-year-old girl with acute myeloid leukemia who presented with massive hyperleukocytosis and neurological deficit due to intracerebral hemorrhage. Surgical intervention was considered but ultimately not undertaken because of the presence of massive hyperleukocytosis, thrombocytopenia, hypokalemia, and considerable discrepancy between the oxygen saturation values determined mechanically and by peripheral oximetry. Aggressive treatment of the hyperleukocytosis was immediately started, which improved the patient's overall condition and rendered surgical intervention unnecessary. This report shows that immediate treatment of massive hyperleukocytosis and critical interpretation of laboratory results in patients with hyperleukocytosis are warranted.