SNCASO (abbreviated from Société nationale des constructions aéronautiques du sud-ouest, or commonly, Sud-Ouest) was a French aircraft manufacturer, which originated on November 16, 1936, from the merger of the factories of Bleriot of Suresnes, Bloch of Villacoublay and Courbevoie, SASO (Société Aéronautique du Sud-Ouest) of Bordeaux-Merignac, UCA (Usine de Construction Aéronautique) of Bordeaux-Begles, Societe Aerienne Bordelaise (SAB) of Bordeaux-Bacalan and Liore et Olivier of Rochefort.

SNCASO built a factory in Deols in 1936.

On March 1, 1957, SNCASO merged with SNCASE (Société nationale de constructions aéronautiques du sud-est), to form the state owned Sud Aviation.