Analytical calculations and recent N-body numerical experiments have suggested that a large fraction of mass in our Galaxy is in a form of clumpy, virialized substructures that can be as light as 10-6 solar masses with an expected number density of 500 pc-3 at the Solar radius. If dark matter is composed by weakly interactive particles with masses in the range 50 Gev-10 Tev, then indirect detection dark matter detection could be possible by observing the gamma-ray annihilation photons produced within these minihalos.
In this talk I estimate the expected Galactic and extragalactic annihilation flux under the assumption that the bulk of dark matter is composed by neutralinos. I analyze the spectral features and the spatial distribution of the gamma-ray signal and compare them with the sensitivities of satellite-borne experiments such as GLAST. The results show that the possible detection of minihalos is indeed very challenging.