Nilo-Saharan refers to the language family in the Nile River and Sahara Desert region.

Joseph Greenberg, in 1963, proposed the recognition of the Nilo-Saharan language family, grouping together numerous languages of Uganda, Ethiopia, Sudan and Chad, for many of which no generally accepted family links had previously been suggested. Greenberg's proposals have been partly confirmed by later research. The languages and language groups do differ quite radically from one another, suggesting that many thousands of years have passed since the postulated proto-Nilo-Saharan language may have been spoken.

The Nilo-Saharan region extends along the southern reaches of the Nile River, along the Great Rift Valley, as far south as modern Tanzania, and westward into Congo (formerly Zaire).

Nilo-Saharan covers the smallest geographical area of all the African language groups. It is also the least clearly defined group, there being great variety within its constituent languages. It includes the Nilotic languages of the Chari-Nile group, such as Dinka and Nuer.

Nilo-Saharan is spoken in east-central Africa around the southern Nile, Chari, and Niger rivers. The group is a small one, and speakers are often found in 'islands' surrounded by other languages. The largest member is Eastern Sudanic, which includes the group of languages known as Nilotic. Nilotic languages are spoken in southern Sudan, Uganda, western Kenya, and northern Tanzania. Nubian is also an Eastern Sudanic language, spoken along the Nile south of Aswan.

The Nilo-Saharan language stock has six branches: Songhai (spoken in Mali), Saharan (including languages spoken both near Lake Chad, as in Kanuri, and in central Sahara), Maban (a group of tongues found east of Lake Chad), Furian (comprising only Fur, an important language of Sudan), Koman (a group of languages of Ethiopia and Sudan), and Chari-Nile, the principal branch of Nilo-Saharan, composed of the Eastern Sudanic languages, the Central Sudanic languages, and two additional tongues, Kunama and Berta; the Chari-Nile tongues are spoken in Sudan, Congo (Kinshasa), Uganda, Cameroon, Chad, the Central African Republic, Kenya, mainland Tanzania, and Ethiopia. The Eastern Sudanic subdivision of Chari-Nile itself has ten branches, the two most important of which are Nubian and Nilotic, both found in Sudan. Nubian is unique among modern African languages in that it has written texts of the medieval period. The Nilotic tongues include Shilluk, Dinka, Nuer, Masai, Turkana, Nandi and Suk. The Central Sudanic subdivision of Chari-Nile consists of a number of languages, among them Mangbetu, spoken in Congo (Kinshasa), and Efe, used by the pygmies. Like the Niger-Congo languages, most of the Nilo-Saharan languages use tones; some Nilo-Saharan tongues inflect their nouns according to case, and still others have gender. The verb in many Nilo-Saharan languages has a system of verb derivation.

According to Ethnologue there are 194 languages in the Nilo-Saharan language family :