Abstract: Astrophysics provides interesting constraints on the properties of dark matter particles and on possible extensions of the Standard Model. In particular, I will discuss the gamma-ray constraints on "MeV dark matter", recently proposed to explain the 511 keV line observed by INTEGRAL/SPI. Furthermore, I will briefly discuss how to use the EGRET gamma-ray data on the diffuse Galactic emission to set strong constraints on theories with extra-dimensions. I will conclude my presentation with an update on indirect dark matter searches, also in light of the recent HESS, CANGAROO and VERITAS high-energy observations of the Galactic center.