The field of oral medicine is fundamental to the practice of general medicine as well as dentistry, oral surgery, and other special fields of medicine concerned with diseases of organs beneath the oral cavity. Disorders of the oral mucosa may reflect many dermal and internal diseases, and may focus the physician's diagnostic attention to systemic pathological conditions which otherwise could be misdiagnosed. As to their morphological appearance, however, the oral mucosa shows other forms of reactivity than the skin. When the dermal and oral manifestations of many skin diseases are compared the influence of distinct local factors on the intraoral clinical picture becomes evident. This comparative view, as well as the dermatologist's practical experience that many dermatoses either spread to, or even are restricted to the oral mucosa, may explain why most dermatologists are very interested in oral diagnosis. In this report, the interdisciplinary view and some aspects of clinical stomatology are stressed which are of actual interest in oral diagnosis and therapy. The following topics are dealt with: Diseases with aphthous lesions, Allergic reactions to drugs, Pemphigus and pemphigoid disorders, Oral infections by Candida albicans, Melkersson-Rosenthal syndrome, Lingual anomalies of different types, Leukoplakias.