We present calculations of the band structure, density of states and the real and imaginary parts of the dielectric functions in intrinsic TIN and AlN, both for wurtzite and the zinc-blende polytypes. They are based on the local density approximation (LDA) within the density functional theory (DFT), employing the first-principles, full-potential linearized augmented plane wave (FPLAPW) method. We correct the band gap of the AlN by using a quasi-particle method proposed by Bechstedt and Del Sole. The calculated energy gaps, lattice constants and dielectric constants for AlN are in good agreement with available experimental values while for TIN there is no experimental investigation. (c) 2005 Elsevier B.V. All rights reserved.