Objective To investigate the clinical significances of white blood cell (WBC) count at ultra-early phase (on admission) of acute traumatic brain injury (TBI).Methods Clinical data of 114 patients (96 males and 18 females) with acute TBI were collected.Age was 11-86 years (mean,49 years).According to the Glasgow Coma Scale (GCS),all patients were divided into mild (13-15 points,28 cases),moderate (9-12 points,46 cases) and severe (3-8 points,40 cases) groups.According to the intracranial pressure,86 patients monitored were grouped in low-(＜ 20 mmHg,33 cases),middle-(20-29 mmHg,25 cases) and high-intracranial pressure (＞ 30 mmHg,28 cases) groups.All patients were divided into craniotomy (45 cases) and non-craniotomy (69 cases) groups.WBC count was recorded and compared among groups.According to the WBC count,all patients were divided into low-WBC group (＜ 10 × 109/L,20 cases),moderate-WBC group (10-20 × 109/L,69 cases) and high-WBC group (＞ 20 × 109/L,25 cases).Glasgow Outcome Scale (GOS) was compared among groups.Results WBC counts in mild,moderate and severe groups were (9.8 ±1.8) × 109/L,(16.7 ± 3.9) × 109/L and (19.6 ± 7.1) × 109/L respectively (P ＜ 0.01).WBC counts in low-,moderate-and high-intracranial groups were (11.1 ± 2.6) × 109/L,(17.2 ± 3.2) ×109/L and (19.4 ± 6.2) × 109/L respectively (P ＜ 0.01).WBC count in craniotomy group was (18.3 ± 6.7) × 109/L,far higher than (14.5 ± 5.3) × 109/L in non-craniotomy group (P ＜ 0.01).Rate of good prognosis differed significantly among low-,moderate-and high moderate-WBC groups (x2 =28.778,P ＜ 0.01).Conclusion In patients with acute TBI,elevated WBC count detected immediately on admission can be used as an important parameter for assessment of injury severity,development and prognosis.