national flag consisting of horizontal stripes of green, yellow, and green with a red hoist triangle and two black stars on the yellow stripe. The flag has a width-to-length ratio of 1 to 2.

Following the revolution in Portugal in April 1974, the possibility of independence for Portuguese colonies opened. Pro-independence forces in São Tomé and Príncipe worked with Portuguese authorities on a timetable that eventually led to independence and a new flag on July 12, 1975. The leading force was the Movement for the Liberation of São Tomé and Príncipe (MLSTP), which had been created in 1960. Its leader, Manuel Pinto da Costa, became the country's first president and is also credited with designing the national flag. Various alternatives, all incorporating the colours associated with pan-African independence (red, yellow, green, and black), were considered and eventually rejected.

The flag finally chosen was the same as that of the MLSTP except that the stripe widths were in a ratio of 2:3:2 instead of being equal. The red triangle at the hoist stands for equality and the independence movement. The two stars reflect the African population living on the two principal islands of which the country is composed. Green is for the luxurious vegetation of the islands, yellow for the tropical sun. The flag is similar to those initially adopted in other former Portuguese territories (Cape Verde (Cape Verde, flag of) and Guinea-Bissau (Guinea-Bissau, flag of)) and in nearby Cameroon (Cameroon, flag of), which had two stars in its flag until May 1975.