In this study we report our experience with 24 patients with acute mastoiditis treated at the University Hospital in Ghent, Belgium. The most common presenting signs and symptoms of acute mastoiditis were an abnormal tympanic membrane (21/24), otorrhea (17/24) and earache (13/24). Postauricular edema and erythema with protrusion of the ear, often used as a diagnostic criterion, was present in only 3 patients. Demineralisation of the trabeculae was the most frequent radiological finding (13/24). Based on CT findings a distinction was made between two groups: acute incipient mastoiditis (13/24) and acute coalescent mastoiditis (5/24). Thirteen patients recovered with conservative therapy consisting of IV antibiotics and early myringotomy with or without placement of a ventilation tube. Mastoidectomy was required in 11 patients. Nine patients presented with a complication of infection extending beyond the mastoid compartment. The results are discussed and the value of CT scanning as a diagnostic tool and decisive element in the choice of therapy is analysed.