We report study of high-pressure phases of AlN compound, using a recent version of the full potential linear muffin-tin orbitals method (FPLMTO) which enables an accurate treatment of the interstitial regions. The Exchange-correlation has been accounted for within LDA using the exchange-correlation potential calculated by Perdew et al. Calculations are given for lattice parameters, bulk modulus and its first derivatives in the wurtzite, zinc-blende, rock-salt, CsCl, NiAs, βSn, the Cinnabar and the hexagonal structures. The results of these calculations are compared with the available theoretical and experimental data.