Article 5 of the 1979 Statutes of Autonomy establishes the Ikurriña as the national flag of the Basque Country and also recognises the flags and insignias of the Historical Territories or Provinces that make up the Basque Autonomous Community.

The flag or "ikurrina" of the Basque Country consists of a green diagonal cross, a white vertical cross and red background.

It was originally designed as the flag of Bizkaia by the brothers Luis and Sabino de Arana Goiri, who respectively inspired and founded Basque nationalism. As a consequence of its use during the first 30 years of the 20th century in all kinds of events and its widespread use throughout the Basque provinces of Gipuzkoa, Alava and Navarra, as well as in the French Basque Country, it ceased to be purely the flag of a political party and was adopted as the Basque flag. In 1936, the Basque Government declared it to be the national emblem.

According to its designers, the Ikurriña was based on the flag of Bizkaia. The red background was taken from the coat of arms of Bizkaia. The green cross of St Andrew (the colour green was an allusion to the oak tree in the coat of arms of Bizkaia) was placed on this red background.  The white cross was also taken from the one superimposed over the oak in this same coat of arms. Its symbolism, according to the intentions of its authors, was simple: Bizkaia, its individual rights and religious faith hierarchically related.