Sud (French) or Sid is one of the ten departments of Haiti and located in southern Haiti. It has an area of 2,653.60 square kilometres (1,024.56 sq mi) and a population of 774,976. Its capital is Les Cayes.

Les Cayes, often referred to as Aux Cayes, is a commune and seaport in the Les Cayes Arrondissement, in the Sud department of Haiti, with a population of 71,236. Due to its isolation from the political turmoil of the capital, Port-au-Prince, it is one of Haiti's major ports, with export trade concentrating on mostly coffee and sugarcane. As the world's largest supplier of vetiver, it exports 250 tons annually of this ingredient of perfume and fragrance manufacturing. Minor exports include bananas and timber.