The use 19F nuclear magnetic resonance (NMR) methods and data analysis for studying biomembranes is discussed. The chemical difficulties of incorporating several designated 19F-labeled amino acid into peptides and the criteria for the optimal choice of label are also discussed. Native cellular membranes or even entire living cell are amenable to 19F NMR after exposure to 19F-labelled molecules, given the total lack of natural abundance background. Any 19F-labeled peptide added externally will show up with high sensitivity in NMR and allow structural conclusions to be drawn.