['To evaluate the safety and efficacy of granulocyte-colony stimulating factor (G-CSF) therapy in patients with hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF).', 'Fifty-five patients with HBV-associated ACLF were randomized into two groups: the treatment group and the control group. Twenty-seven patients in the treatment group received G-CSF (5 μg/kg per day, six doses) treatment plus standard therapy, and 28 patients in the control group received standard therapy only. The peripheral CD34(+) cell count was measured consecutively by flow cytometry. Circulating white blood cell count, biochemical parameters, and other clinical data of these patients were recorded and analyzed. All patients were followed up for a period of 3 mo to evaluate the changes in liver function and survival rate.', 'The peripheral neutrophil and CD34(+) cell counts in the G-CSF group increased on day 3 from the onset of therapy, continued to rise on day 7, and remained elevated on day 15 compared to those of the control group. Child-Turcotte-Pugh score of patients in the treatment group was improved on day 30 from the onset of G-CSF therapy, compared to that in the controls (P = 0.041). Model for End-Stage of Liver Disease score of patients in the treatment group was improved on day 7 (P = 0.004) and remained high on day 30 from the onset of G-CSF therapy (P < 0.001) compared to that in controls. After 3 mo of follow-up observation, the survival rate in the treatment group (48.1%) was significantly higher than that in the control group (21.4%) (P = 0.0181).'] Does granulocyte-colony stimulating factor therapy improve survival in patients with hepatitis B virus-associated acute-on-chronic liver failure?