Background:  Acute invasive fungal rhinosinusitis (AIFRS) is an emerging disease on top of SARS CoV-2 virus infection and associated with severe and fatal prognosis especially in the presence of other immunosuppressive conditions. Aim of study: Identification of the causative agents of AIFRS in COVID-19 patients and its impact on the survival outcome. Methods: This retrospective study was carried out on 70 clinically and radiologically diagnosed AIFRS patients either in concomitant with COVID-19 infection or following recovery. Exudates from the lesions were collected during surgical debridement. Both microbiological and pathological examinations were done to identify the type of the causative fungi followed by assessment of the relation between different type of fungi and the outcome in the affected patients. Results: Positive fungal cultures were detected in 54 cases out of 70 where Mucor species were the most common isolates (42 patients) and only 12 cases were proven to be Aspergillus species. All patients were diabetic and under steroid therapy. Mortality rate was 42.9% and 25% in mucormycosis and aspergillosis respectively. High dose of steroid together with Mucor species infection were the most important risk factors in determining the prognosis and the outcome of the infection. Conclusion: Microbiological diagnosis together with other methods plays an important role in accurate and rapid diagnosis of AIFRS in association with COVID-19 for proper management and improving the outcome.