Interne des Hôpitaux de Paris in 1926, Degos was appointed in 1934 as assistant at the Saint-Louis dermatological department headed by Gougerot, Professor of Dermatology whom he succeeded in 1951.

For 25 years, Degos was fulfilling all the major responsabilities of French dermatology: General Secretary of the French Society of Dermatology, Professor of Dermatology, Chief Editor of the Annales de dermatology and author of a great textbook (Dermatologie) regarded as the bible of the french speaking dermatologists untill his last up-to-date edition in 1981.

Degos described several dermatoses, genodermatose en cocardes in 1947, clear cells acanthoma in 1962 and especially malignant atrophiant papulosis (Degos' disease) in 1942.