Reports concerning the lesions of the skin coverage of the external ear canal in malignant external otitis (M.E.O.) are very few. To evaluate this problem, we studied the skin lesions of 45 skin biopsies from 40 M.E.O. patients, 23 from regions covering the osseous part of the ear structure, seven from the cartilaginous part of the external canal and 15 from both parts. The epidermis was normal in nine, thickened in 16, with acanthotic thickening and pseudoepitheliomatous hyperplasia in 20. In the dermis the amount of collagen was normal, but it was infiltrated by the inflammatory process. Acute inflammation was observed in 16 biopsies, subacute in 23, chronic in six. A mixture of acute and chronic changes was present in 18 biopsies. No major abnormalities of the vasculature could be detected. The distinguishing pathological feature of M.E.O. concerns the typical topographic distribution of the inflammation in the osseous part of the external ear canal.