Background: Sensitization to common Mold allergens is one of the major causes of allergic rhinitis and asthma. Therefore, there is a critical need for standard sensitivity tests including skin prick tests to improve the stability of fungi extracts in traditional allergenic formulations. To address this concern, the present study aimed to develop a formulation to preserve allergenic activity of Mold extracts. Methods: 48 stabilizer formulations were designed and monitored for allergenic activity during a 40-days incubation period at 37 ˚ C using an ELISA. Specifically, the IgE reactivity of allergenic A. alternata extracts were examined. After establishing the most effective stabilizer formulation, we evaluated whether it could protect the allergenic activity of Alt a1, A. fumigatus, and C. herbarum using an IgE inhibition ELISA after 40 days at 37 ˚ C. Results: We demonstrated that the most effective stabilizer formulation was a glycerol-based extract containing Arg and Glu. This formulation had an equal ratio of sucrose, sorbitol and protein and was able to preserve more than 95% of allergenic A. alternata extract activity during a 40-days incubation period at 37 ˚ C. Conclusions: The present study reveals a novel formulation that is an efficient stabilizer of allergenic Mold extract activity and has practical applications in Mold skin prick tests, ELISAs, immunotherapies, and RAST.