Background: There is a need to support the diagnosis of anaphylaxis by objective markers. miRNAs are promising non-coding RNA species that may serve as serological biomarkers, but their use in diagnosing anaphylaxis has not been systematically studied. We aimed to comprehensively investigate serum biomarker profiles (proteins, lipids, and miRNAs) to support the diagnosis of anaphylaxis.Methods: Adult patients admitted to the emergency room with a diagnosis of anaphylaxis (< 3 hours) were included. Blood samples were taken upon emergency room arrival and one month later.Results: Next-generation sequencing of 18 samples (6 anaphylaxis patients in acute and non-acute condition, respectively, and 6 healthy controls) identified hsa-miR-451a to be elevated during anaphylaxis and verified by RT-qPCR in the remaining cohort. The random forest classifier enabled us to classify anaphylaxis with high accuracy using a composite model. We identified tryptase, 9α,11β-PGF2, apolipoprotein A1, and hsa-miR-451a as serological biomarkers of anaphylaxis. These predictors qualified as serological biomarkers individually but performed better in combination. Conclusion:Unexpectedly, hsa-miR-451a was identified as the most relevant biomarker in our data set. We were also able to distinguish between patients with a history of anaphylaxis and healthy individuals with higher accuracy than any other available model. Future studies will need to verify miRNA biomarker utility in real-life clinical settings.