Pure and hydrogen terminated silicon carbide (SiC) nanowires grown along  direction in the wurtzite structure are studied using ab initio density functional theory calculations. The pure wires preserve their crystalline-like topology with only small relaxations on their surface. Also, the pure wires are semiconducting, but their band gap energy decreases with decreasing diameter due to the presence of surface states. As expected, hydrogen saturation induces a broadening of the band gap energy because of the quantum confinement effect. SiC nanowires are also predicted to be very rigid. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.