Résumé
The annihilations of WIMPs that may compose Dark Matter in the Galaxy would produce high energy gamma-rays in the final state. It is shown that the spectrum of the source HESS J1745-290 in the Galactic Center region is unlikely to be interpreted by such a signal. Constraints will be derived on a possible component due to Dark Matter annihilation. Future observations of dwarf spheroidal galaxies are also promising for detecting a possible gamma-ray signal from Dark Matter. The predictions for Sagittarius dwarf spheroidal galaxy in the framework of the supersymmetric and Kaluza-Klein models are also discussed.