Geometries and Si-29 NMR chemical shifts are calculated for silanes SinH2n+2, n = 1,...,5, methylsilanes SiHnMe4-n methoxysilanes SiHn(OMe)(4-n). and methylmethoxysilanes SiMen(OMe)(4-n), n = 0,...,4. Geometries and Si-29 NMR chemical shifts are in satisfying agreement with experiment within LCGTO-DFT at the DZVP/LDA level for geometries and IGLO-III/GGA (GGA = PW9.1PBE) level for shielding constants, which is an improvement to B88PW86. P86PW86 and B3LYP results. If an auxiliary basis is applied to express the Coulomb potential. g-functions have to be included to reproduce SiOSi angles and Si-29 NMR chemical shifts correctly, (C) 2002 Published by Elsevier Science B.V.