We have studied structural, electronic, elastic and dynamical properties of NiSi2 by employing the plane wave pseudopotential method based on density functional theory within the local density approximation. The calculated lattice constant, bulk modulus and first-order pressure derivative of the bulk modulus are reported and compared with earlier available experimental and theoretical calculations. Numerical first-principles calculations of the elastic constants were used to calculate C11, C12 and C44 for NiSi2. The calculated electronic band structure has been compared with angle-resolved photoemission spectroscopy experimental data along the  and  symmetry directions. A linear response approach to density functional theory is used to derive the phonon dispersion curves and phonon partial density of states. Atomic displacement patterns for NiSi2 at the , X and L symmetry points are also presented.