A DFT investigation of substitutionally doped fullerenes MC59 of second- and third-row transition metalsshows that their stability increases toward the right-hand side of the d-block. Whereas the structural deviationfrom that of C60 depends on the size of the metal atom, stability is governed by electronic properties of thetransition metal atom. A range of MC59 compounds of group 6−8 metals are predicted to have sufficientstability for experimental observation.