Abstract
We study the Laguerre-Hahn forms, that is to say those whose formal Stieltjes function satisfies a Riccati equation. We give the definition of the class of a Laguerre-Hahn form. We carry out the complete description of the symmetric forms of class s=1. Essentially, three canonical cases appear. Some particular cases are exhibited which refer to well-known orthogonal sequences. In general, the problem of representing these forms is open.