A 12-year-old boy developed fever, trigeminal pain, altered mental status, and a sixth cranial nerve palsy, features of Gradenigo syndrome. Diffusion-weighted MRI demonstrated restricted diffusion in the ipsilateral petrous apex, identifying an abscess as the cause of his manifestations. The patient was successfully treated with broad-spectrum antibiotics. This is the first report demonstrating the use of diffusion-weighted imaging in Gradenigo syndrome.