The electronic, elastic and dynamical properties of the quaternary alloy FeNiMnAl have been investigated using a pseudopotential plane wave method within the generalized gradient approximation (GGA). We determined the lattice parameters and the bulk modulus B. In addition, the elastic properties such as elastic constans (C-11, C-12 and C-44), the shear modulus G, the young modulus E, the poisson's ratio sigma and the B/G ratio are also given. The FeNiMnAl Heusler alloy exhibit a ferromagnetic half-metallic behavior with the total magnetic moment of 4.02 mu(B). The phonon dispersion of FeNiMnAl has been performed using the density functional theory and the direct method with 2x2x2 supercell.