The national flag of Romania (Romanian: drapelul României) is a tricolour. The Constitution of Romania states that "The flag of Romania is tricolour; the colours are arranged vertically in the following order from the flagpole: blue, yellow, red". The flag has a width-length ratio of 2:3; the proportions, shades of colour as well as the flag protocol were established by law in 1994, and extended in 2001.

The flag is very similar to the civil flag of Andorra and the state flag of Chad. The similarity with Chad's flag, which is identical apart from allowing a broader range of shades of blue, yellow and red, has caused international discussion. In 2004, Chad asked the United Nations to examine the issue. However, then-president of Romania Ion Iliescu announced that there would be no changes to the flag. The flag of Moldova is similar to the Romanian tricolour, except that it has a 1:2 ratio, a lighter shade of blue, a slightly different shade of yellow, and the Moldovan coat of arms in the middle. The civil ensign of Belgium uses black rather than blue.