The term "immunocompromised host" is generally applied to a variety of patients with various immune defects. Invasive rhinosinusitis is defined by the presence of local inflammation, with vascular and osseous necrosis with extensive soft tissue extension, and occurs almost exclusively in immunocompromised patients. Fungi have been increasingly recognized as important pathogens in severe acute and chronic sinusitis in immunosuppressed hosts. Earlier recognition of the disease, medical attention specific to the patient's needs are required. After medical remission, significant complications of invasive fungal infection may be seen. Patients should be followed in the long-term, until remucosalization of the sinuses.