In immunocompromised patients, symptoms and the pathogen spectrum of sinusitis are frequently atypical. If progressive loss of vision occurs, an infection of the anterior skull base or nasal sinuses should be considered. We report on four patients with orbit-associated symptoms. CT-imaging revealed bony defects in sinus borders to orbits or endocranium. In all the cases immediate surgical drainage was performed because complications following sinusitis were suspected. Histopathological diagnosis revealed two cases of aspergillosis and mucormycosis. The possibility of opportunistic infections by saprophytic fungi must be taken into account in immunocompromised patients, as they may endanger both vision and survival. Immediate diagnosis and therapy are essential. Nowadays, therapeutic success can be achieved due to advances in antimicrobial therapy, hyperbaric oxygen therapy and treatment of the underlying disease. Radical procedures like orbital exenteration must be considered in all cases. The current state of diagnostics, therapy and prognosis is discussed based on these case reports and the recent literature.