A review with 91 refs. The use of solid-state NMR as a tool to det. the structure of membrane mols. is reviewed with a particular emphasis on techniques that provide information on orientation or order. Expts. reported here have been performed in membranes, rather than in micelles or org. solvents. Several ways to prep. and handle the samples are discussed, like sample orientation and magic-angle spinning (MAS). Results concerning lipids, membrane peptides and proteins are included, as well as a discussion regarding the potential of such methods and their pitfalls. [on SciFinder (R)]