In this talk, I will address the problem of the ergodicity of chaotic billiards. The most famous examples of chaotic billiards are the Sinai billiard and the Bunimovich stadium. Their ergodicity, as well as the Bernoulli property, was established a long time ago. Many other billiards are know to be chaotic. I am interested in a class of chaotic billiards that are generalizations of the stadium billiard: the boundary of their tables contains curves acting as focusing mirrors and straight segments. In the first part of the talk, I will surveys back facts and results about chaotic billiards, then I will discuss a result on the ergodicity of generalized stadia recently obtained in collaboration with R. Markarian.