The initial application is reported of single-crystal Mn-55 NMR spectroscopy, and associated orientation dependence studies, to single-molecule magnets (SMMs). The studies were performed on two members of the Mn-12 family of SMMs, [Mn12O12(O2CMe)16(-)(H2O)(4)]center dot 2MeCO(2)H center dot 4H(2)O (Mn-12-Ac) and [Mn12O12(O2CCH2Br)16(-)(H2O)(4)]center dot 4CH(2)CL(2) (Mn-12-BrAC). Single-crystal spectra give a dramatic improvement in the spectral resolution over oriented powder spectra, allowing the clear observation of quadrupolar splittings, the determination of quadrupole coupling parameters (e(2)qQ), and an assessment of the symmetry-lowering perturbation of the core of Mn12-Ac by hydrogen-bonding interactions with lattice solvate molecules of crystallization. The results emphasize the utility of single-crystal NMR studies to probe the cores of these magnetic molecules.