(31)P and (15)N solid-state NMR with the magic angle-oriented sample spinning (MAOSS) strategy was used to investigate the effect of two model peptides on phospholipid bilayers mimicking biological membrane. One of the peptides, alamethicin, used as a reference of transmembrane alignment, has been shown to disrupt the lipid bilayer organisation, affecting the DMPC packaging. On the other hand, a alpha-helix alanine-rich peptide, K(3)A(18)K(3), with a (15)N labelled alanine, did not present any effect in the DMPC bilayer organisation. The mean orientation of this peptide in the bilayer gave a transmembrane alignment of about 80%.