We report first principles calculations of structural, electronic, elastic and optical properties of Mg-based compounds in zinc blende and rocksalt structures employing the density functional theory (DFT) within the local density approximation (LDA) using the full potential linearised augmented plane wave (FPLAPW) method. Results include lattice parameters, band structure, total and partial density of states, charge density and optical properties of MgS, MgSe and MgTe semiconductors in zinc blende and rocksalt structures. (C) 2003 Elsevier B.V. All rights reserved.