Twenty-three cases of progressive necrotizing (malignant) external otitis were reviewed. Radiographic evaluation was correlated with clinical disease. CT scanning accurately demonstrated subtle foci of involvement in the skull base which may be clinically unsuspected or go undetected with other studies. Central skull base erosion indicates advanced disease and selects those patients requiring extended antibiotic therapy. Soft tissue thickening of the parapharyngeal space and roof of the nasopharynx also implies advanced disease requiring prolonged therapy. Soft tissue improvement can be visualized on CT. While CT scanning demonstrates the progression of bony disease, it cannot be used to follow resolution of central skull base osteomyelitis. Radionuclide scans provide information regarding the overall extent of the inflammatory process.