Here's a breakdown:

* Hydrogen: Makes up about 75% of the mass of a star.

* Helium: Makes up about 23% of the mass of a star.

* Other Elements: The remaining 2% is made up of trace amounts of heavier elements like carbon, oxygen, nitrogen, and iron.

It's important to note that the exact composition can vary slightly depending on the star's age, size, and location in the universe. However, hydrogen and helium are the dominant elements in most stars.