Background: Allergic fungal sinusitis is a non-invasive pansinusitis that occurs in young immunocompetent individuals, with a strong history of atopy and elevated levels of total immunoglobulin E and peripheral eosinophilia. Objective: The main target of the study was to know the relation between complicated allergic fungal sinusitis and the mycologic profile of the causative fungal species, as regards the genus and species of the isolated fungus, its antifungal susceptibility and its ability to produce destructive extracellular metabolic products and toxic agents. Patients and Methods: Our cross sectional research included 50 individuals diagnosed with complicated allergic fungal rhinosinusitis who attended to the ENT outpatient clinic. All the studied patients were evaluated by full history, complete ENT examination, radiological evaluation, laboratory investigations and endoscopic sinus surgery. Results: Aspergillus spp., particularly Aspergillus fumigatus and Aspergillus flavus, are the most often identified agents in allergic fungal rhinosinusitis. A multifaceted strategy to treat allergic fungal rhinosinusitis is necessary; surgery is the primary treatment for allergic fungal sinusitis. Corticosteroid treatment in its entirety is presently the gold standard of medical management, whereas alternative pharmacological treatments such as antifungals, antimicrobials, leukotriene modulators, and immunotherapy are reserved for those who are insufficiently responsive.. Conclusions: The most frequent kind of fungal rhinosinusitis is allergic fungal rhinosinusitis. It is found in immunecompetent youth who have a history of allergic rhinitis and/or asthma. Allergic fungal rhinosinusitis has a relatively slow and indolent clinical course, but results in the growth of bone walls, resulting in their thinning or weakening and final erosion.