Background: To investigate the utility of established prognostic scoring systems, such as the Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential Organ Failure Assessment (SOFA) score, and Glasgow Coma Scale (GCS), for patients admitted to a neurosurgical intensive care unit (ICU).Methods: Among neurosurgical patients admitted to the neurosurgical ICU in a tertiary hospital from January 2015 and December 2022, only patients who had an ICU stay exceeding three days were included. The primary endpoint was in-hospital mortality. Results: In this study, a total of 3,417 patients were enrolled in the study. Of these, 3,052 (89.3%) survived until hospital discharge. Both the APACHE II and SOFA scores were significantly higher in non-survivors than in survivors (p<0.001 for both). Conversely, GCS and GCS motor score (GCS M) were substantially lower in non-survivors (p<0.001). Among the commonly used scoring systems, the APACHE II score emerged as the most effective predictor of in-hospital mortality (C-statistic of 0.887, 95% confidence interval: 0.869–0.887). Remarkably, the GCS M proved to be equally effective as the SOFA score in predicting in-hospital mortality (p=0.435) and offered the additional advantage of being simpler to use.Conclusions: Our findings indicate that these scoring systems offer valuable insights into the clinical prognosis of patients in the neurosurgical ICU. Moreover, the GCS M stands out as a feasible and reliable metric for predicting in-hospital mortality among neurosurgical ICU patients.