Objective We aim to explore the potential association between serum gamma-glutamyl transferase levels and functional outcome after aneurysmal subarachnoid hemorrhage in a Chinese population. Methods A total of 386 aneurysmal subarachnoid hemorrhage patients were included in the study from September 2007 to February 2015. Baseline serum gamma-glutamyl transferase levels and 6-month follow-up functional outcomes were determined. A poor outcome was defined as a modified ranking scale score of ≥ 3. The multivariable logistic model was used to analyze the relationship between serum gamma-glutamyl transferase and clinical outcomes after aneurysmal subarachnoid hemorrhage. Results The adjusted poor outcome rates of patients with gamma-glutamyl transferase levels of < 30 U/L, 30-50 U/L and ≥ 50 U/L were 16.7%, 19.6%, and 34.4%, respectively(P < 0.01). The age-sex and multivariable adjusted odds ratios(95% confidence intervals) of poor prognosis comparing the top group(≥ 50 U/L) with the lowest group(< 30 U/L) were 5.76(2.74-12.13), 6.64(2.05-21.52), and 6.36(1.92-21.02). A significant linear trend existed between gamma-glutamyl transferase level and aneurysmal subarachnoid hemorrhage prognosis. This association was also observed among nondrinkers. Conclusion Patients with higher gamma-glutamyl transferase levels were more likely to have a poor prognosis. Serum gamma-glutamyl transferase can be considered to be an independent predictor of functional outcomes after aneurysmal subarachnoid hemorrhage. Objective We aim to explore the potential association between serum gamma-glutamyl transferase levels and functional outcome after aneurysmal subarachnoid hemorrhage in a Chinese population. Methods A total of 386 aneurysmal subarachnoid hemorrhage patients were included in the study from September 2007 to February 2015. Baseline serum gamma-glutamyl transferase levels and 6-month follow-up functional outcomes were determined. A poor outcome was defined as a modified ranking scale score of ≥ 3. The multivariable logistic model was used to analyze the relationship between serum gamma-glutamyl transferase and clinical Results after aneurysmal subarachnoid hemorrhage. Results The adjusted poor outcome rates of patients with gamma-glutamyl transferase levels of <30 U / L, 30-50 U / L and ≥ 50 U / L were 16.7%, 19.6%, and 34.4% respectively (P <0.01). The age-sex and multivariable adjusted odds ratios (95% confidence intervals) comparing the top group (≥ 50 U / L) with the lowest group (<30 U / L) were 5.76 (2.74-12.13), 6.64 (2.05-21.52), and 6.36 (1.92-21.02). A significant linear trend existed between gamma-glutamyl transferase level and aneurysmal subarachnoid hemorrhage prognosis. Association was also observed among nondrinkers. Conclusion Patients with higher gamma-glutamyl transferase levels were more likely to have a poor prognosis. Serum gamma-glutamyl transferase can be considered to be an independent predictor of functional outcomes after aneurysmal subarachnoid hemorrhage.