The electronic and magnetic properties of heusler alloys compounds Fe2MnAl, Fe2MnSi and Fe2MnGa are described in this article. We have applied the full-potential linearized augmented plane waves plus local orbitals (FP-L/APW) method based on the density functional theory (DFT). Generalized-gradient approximation (GGA) is used for the exchange and correlation potential. The calculated atomic resolved densities of states of Fe2MnAl, Fe2MnSi indicate half-metallic behavior with vanishing electronic density of states for minority spin at the Fermi level, which yields perfect spin polarization while for Fe2MnGa the full electron energy of ferromagnetic metallic fcc phase (μfcc =6.11μBf.u.) is lower by about 0.06 meV (0.69 K) than that of ferrimagnetic half-metallic phase with L21 structure (μL21 = 2.036μBf.u.).