Malignant external otitis is an unusual but serious and potentially fatal condition that has only recently been described. It is an invasive pseudomonal infection of the external auditory canal and deep periauricular tissues that characteristically involves the bone and adjacent cartilaginous structures, and it may lead to osteomyelitis of the base of the skull. It typically occurs in elderly diabetic patients. Malignant external otitis can cause severe pain, necrosis of the external auditory canal and progressive palsies of the facial and cranial nerves. Treatment consists of debridement of external auditory canal granulation tissue and long-term therapy with an antipseudomonal cephalosporin or an antipseudomonal penicillin plus an aminoglycoside.