Fungal sinusitis has a nonspecific clinical presentation, is refractory to standard medical treatment and may produce expansion and erosion of the sinus wall. Various factors have been implicated in the development of fungal sinusitis: anatomical factors in the osteomeatal complex, tissular hypoxia, traumatic factors, massive exposure to fungal spores, allergy and immunosuppression. Our study of four cases diagnosed in the department included the clinical, pathological, and radiological features of fungal sinusitis. Five forms are described. Bacterial infection often occurs. The diagnosis of fungal sinusitis requires a high level of clinical and pathological suspicion. Before surgery, fungal sinusitis is suggested by the clinical and radiological features, and is confirmed by histological study. Culture of the tissue sometimes leads to identification of the fungus. Surgical removal of the infection is the main treatment for every form of fungal sinusitis.