The presence of abnormally high levels of Aspergillus fumigatus-specific immunoglobulin (Ig) G antibodies can serve as a diagnostic criterion for severe conditions like allergic bronchopulmonary and chronic pulmonary aspergillosis. This study aimed to determine a reference range of A. fumigatus-specific IgG levels within a healthy adult Omani population. Methods: This study took place during November 2015 at the Sultan Qaboos University Hospital, Muscat, Oman. The sera of 125 healthy Omani blood donors were tested for A. fumigatus specific IgG levels using an automated fluorescence enzyme immunoassay. Results: Initially, the data were not normally distributed; however, log transformation and the exclusion of four outliers resulted in an acceptable Gaussian distribution. The reference range was 2.0–68.7 mgA/L at the 2.5th and 97.5th percentiles, respectively, with 90% confidence intervals of 2.0–3.0 mgA/L and 48.0–76.0 mgA/L, respectively. Conclusion: The A. fumigatus specific IgG reference range within a healthy adult Omani population was comparable to those reported in other populations