Purpose: The incidence of glufosinate poisoning is gradually increasing, and it can be fatal if severe poisoning occurs. However, factors useful for predicting the post-discharge neurological prognosis of patients who have ingested glufosinate have yet to be identified. Our objective was to evaluate the utility of the acute physiology and chronic health evaluation (APACHE) II score measured in the emergency department for predicting the neurological prognosis. Methods: From April 2012 to August 2014, we conducted a retrospective study of patients who had ingested glufosinate. The outcome of the patients at discharge was defined by the Cerebral Performance Category Score (CPC). The patients were divided into a good prognosis group (CPC 1, 2) and a poor prognosis group (CPC 3, 4, 5), after which the APACHE II scores were compared. The Hosmer-Lemeshow test and the area under the receiver operating characteristic (ROC) curve from patients determined calibration and discrimination. Results: A total of 76 patients were enrolled (good prognosis group: 67 vs poor prognosis group: 9). The cut-off value for the APACHE II score was 12 and the area under the curve value was 0.891. The Hosmer and Lemeshow C statistic χ2 was 7.414 (p=0.387), indicating good calibration for APACHE II. Conclusion: The APACHE II score is useful at predicting the neurological prognosis of patients who have ingested glufosinate.