The notion of "Siegel domains" was introduced by . It was then shown that every homogeneous bounded domain is holomorphically equivalent to a Siegel domain (of the second kind) determined uniquely up to an affine isomorphism ([15] . The purpose of the present note is to show that this classification can also be obtained immediately from my previous result on linear imbeddings of self-dual cones ([10a]).Our method is based on the following two observations: (I) There are natural equivalences between the three categories of (punctured) self-dual cones, the corresponding reductive Lie algebras (with fixed Cartan involutions), and formally real Jordan algebras ( § 1).(II) There is a natural bisection between the set of isomorphism classes of quasi-symmetric Siegel domains and that of equivalence classes of the pairs formed of a self-dual cone and a (linear) "representation" of it ( §3, Proposition 2).