Background: Pollen-allergy is common in Austria. The present study investigated if the use of major pollen-allergens on top of extract-based diagnosis may improve the diagnostic accuracy and if this additional knowledge helps to identify patients eligible for allergen-specific immunotherapy (AIT). Methods: In this retrospective database analysis patients sensitized to a grass, birch, ash-tree, mugwort or ragweed were investigated and results of pollen extracts compared to the respective major allergens (Phl p 1, Bet v 1, Ole e 1, Art v 1, Amb a 1) were assessed. Furthermore, extract- and MD- results of patients double-sensitized to both tree-extracts or both weed-extracts were compared. In patients with discrepant results, their charts were reviewed to define if this difference was clinically relevant in regard to their doctors´ AIT-decision. Results: 4234 patients (age 1.2-89.7yrs) could be included in the analyses. There was high agreement between extract-based IgE results and major allergens concerning single-sensitization to grass/Phl p 1+5 (94.4%), birch/Bet v 1 (94.4%), and ash-tree/Ole e 1 (82.9%), with lower agreement between mugwort/Art v 1 (64.1%) and ragweed/Amb a 1 (73.8%). Among patients double-sensitized to both tree pollen extracts only 76% were also sensitized to both major allergens (Bet v 1 and Ole e 1) and therefore suitable for AIT. In patients double-sensitized to both weeds, only 25% were also sensitized to both major allergens (Art v 1 and Amb a 1), 46.2% of mugwort extract positive patients tested negative for Art v 1. Of these patients, 41.3% were recommended a ragweed AIT as their Amb a 1 results were positive. Conclusion: MD can improve diagnostic accuracy in patients with pollen-allergy and should be implemented in standard clinical care, especially when double-sensitization to allergens of plants with overlapping pollen seasons cannot be clearly discerned by patients´ symptoms alone.