Sphenoid sinusitis is an uncommon infection, but an early diagnosis and appropriate treatment is important because of its serious complications. We report 4 patients (28, 28, 37 and 28 years old) admitted to a department of infectious diseases with meningitis, sepsis and orbital cellulitis as complications of acute sphenoidal cavity infection. The cases illustrate the value of computed tomography (CT) scan of the sphenoid sinus in the evaluation of patients with clinical features suspicious of sphenoid sinusitis.