The Hippocratic texts give evidence of the first structured interest in skin diseases. Nosological preoccupations, then at their beginning, put the stress on the connections between general pathology and diseases affecting the skin, and by creating a vocabulary. The Hippocratic texts give evidence of the first structured interest in skin diseases. Nosological preoccupations, then at their beginning, put the stress on the connections between general pathology and diseases affecting the skin, and by creating a vocabulary drawn from the vegetal world initiated a long-lasting relationship between dermatology and botany. The centuries which followed witnessed a wealth of descriptions which, thanks in particular to the works of Celsus, Galen and the Arab authors, led to the formation of true medical encyclopaedias, although the diagnosis of skin diseases could not be approached. The outline of a rational dermatological thinking did not appear until the 17th century with Haffenreffer, Riolan and Willis, all influenced by Malpighi, Harvey and Sydenham. Then came the 18th century with Astruc, Turner and Lorry. But it was in fact J. Plenck who devised the first nosology that could be used in clinical practice by creating the elementary lesion principle, later revised and refined by Willan and Bateman. In contradistinction with this artificial nosology, the French school of Alibert endeavoured to set up a natural nosology unfortunately spoiled by a certain lack of pragmatism. In the second half of the 19th century three main schools of thought emerged: Hebra's, who raised the nosological approach to an anatomical level, Hardy, Bazin's, who gave predominance to diathesis, and Wilson's, who attempted a synthesis of the first two schools. At the dawn of the 20th century the dogmatism of morphological systematization seemed to wane and be superseded by an aetiological approach, then reappeared in Degos' treatise published in 1953. The latest nosologies acknowledge the importance of clinical data but give first rank to the physiopathology of diseases, sometimes replacing the anatomical systematization by a relative biological systematization which evolves with technological advances.