* Tanzania: Swahili is the official language of Tanzania and is widely spoken throughout the country.
* Kenya: Swahili is one of the official languages of Kenya and is widely used in government, education, and commerce.
* Uganda: Swahili is a national language of Uganda and is used in government and education, although it is not as widely spoken as English.
* Rwanda: Swahili is a national language of Rwanda and is used in education and some government functions.
* Burundi: Swahili is a national language of Burundi and is used in education and some government functions.
It's also important to note that Swahili is spoken in other African countries, but it's not considered a major language in those nations.