Otitis externa is one of the most common diseases in ORL practice, during summer; the treatment of otitis externa may be simple and easy or protracted and frustrating, also with fatal outcome. Many local factors may interfere with the normal defences against infections in the external auditory canal. Removing or dissolving the cerumen by water or other instruments eliminates an important barrier to infections: its acids inhibit the growth of bacteria (Staphylococcus aureus and Pseudomonas aeruginosa) and fungi (Aspergillus). Also skin abrasions or irritation, allergic diseases and many systemic condition like anaemia, vitamin deficiency, endocrine disorders (diabetes) and various forms of dermatitis cause a lower resistance to infections in external auditory canal. Even if the prognosis remains benign in the majority of cases, important complications could appear like: malignant otitis externa, facial nerve paralysis, tympanic bone osteomyelitis, pericondrytis. Successful treatment depends on a proper diagnosis and therapy: the most important factor in the treatment is repeated debridement of the external auditory canal by the physician. The use of Castellani' Tintura rubra, hydroalcoholic solution of phenic fuchsin, can be very effective for bacteria and mycotic eradication. Culturing of ear canal infection could be performed on the second or third visit if the otitis externa is not responding to therapy. Complication are not frequent, but malignant otitis externa can be mortal. Dermatological consultation is often necessary for correct diagnosis.