Phosphorus-31 Magic-Angle Spinning (MAS) NMR is shown to be an extremely useful and accurate method for the determination of the enantiomeric purity for chiral organophosphorus compounds. "P and "C chemical shielding tensors in racemic and enantiomeric crystals of organophosphorus compounds vary because of different crystal symmetries. This implies that solid-state 31P (13C) MAS spectra of an enantiomerically impure sample reveal separate signals from the racemic and enantiomer crystallites. Simple integration (or deconvolution) of the MAS NMR signals can thus be used to determine the enantiomeric purity of the sample. For organophosphorus compounds the application of this technique to 31P MAS NMR is of particular interest due to the high sensitivity and large shielding anisotropy of the 31P nucleus. KEY WORDS 31P MAS NMR Enantiomeric purity