The connection of Dark Matter to our particle physics model is still one of the open cosmological questions. In these proceedings I will argue that axinos can be successful Cold Dark Matter candidates in models with Supersymmetry and the Peccei-Quinn solution of the strong CP problem. If they are the Lightest Supersymmetric Particle (LSP), they can be produced in the right abundance by thermal scatterings and out of equilibrium decays of the Next-to-Lightest Supersymmetric Particles (NLSPs). Moreover if the NLSPs are charged, their decay could help us understand which is the LSP, e.g. between axino and gravitino.

7 pages, 4 figures, contribution to the Proceedings of the International Workshop "The dark side of the Universe", Madrid, June 2006