Fischer type carbenes of the chromium triad (CO)(5)M=CH2, M = Cr, Mo, W, have been subjected to a density functional study. It was found that the self consistent treatment of nonlocal density corrections has a substantial influence on the M=C geometry with bond extensions of 5 pm for all three metals. Further, for the tungsten compound the contributions from relativistic corrections to the W-C bond distances amounts to 7-8 pm. As far as bond energies are concerned, it is sufficient to optimize the geometries within the local density approximation and to calculate the final energies with nonlocal corrections added as a perturbation. The relativistic corrections to the M=C bond energy are of special importance in the tungsten case.