This paper examined miR-181a expression in the serum of patients with acute liver failure (ALF) and investigated the impact of its expression in the prognosis of ALF patients. A total of 112 ALF patients (ALF group) and 100healthy controls during the same period (control group) were recruited as study subjects, and ALF patients were separated into the survival group and the death group. Serum ALT, AST, SCr, TBil, PTA, and International Normalized Ratio (INR) indices as well as serum miR-181a expression were assessed by using a fully automated biochemistry analyzer and RT-qPCR. Patients in the ALF group were evaluated using the Model for End-Stage Liver Disease (MELD) score. Correlation between serum miR-181a expression and MELD scores of ALF patients was processed by Pearson correlation analysis, and the diagnostic value of miR-181a level for the occurrence of ALF was estimated by ROC curve analysis. Multivariate logistic regression analysis was executed to assess the factors influencing the occurrence of death in ALF patients. ALF patients had higher levels of ALT, AST, TBiL, SCr, INR and miR-181a and lower PTA levels in comparison to healthy controls. Serum miR-181a expression level in ALF patients revealed a significant positive correlation with MELD score. Multivariate logistic regression analysis unveiled that TBil, INR, SCr, and miR-181a were the independent risk factors for the occurrence of death in ALF patients, and that PTA was an independent protective factor for the prognosis of ALF patients. miR-181a exhibited a favorable diagnostic value in ALF and its prognosis. miR-181a expression is upregulated in the serum of ALF patients, and it can be utilized as an indicator for ALF diagnostic and prognostic assessment.