Nine new analogues of substance P (SP) were designed using quantitative sequence‐activity models based on the amino acid z‐scales with PLS as the statistical method and the GOLPE procedure for variable selection. The nine SP analogues were synthesised by solid‐phase peptide synthesis and tested for affinity to the NK‐1 receptor from rat brain with radio receptor assay using [125I]‐Bolton‐Hunter substance P as labelled ligand. All of the new substance P analogues showed high affinities, with IC50 values of less than 0.8 nM. One analog, Lys‐Arg‐Ala‐Lys‐Phe‐Met‐Met‐Phe‐Phe‐Gly‐Leu‐Let‐NH2, showed a exceptional high affinity for the NK1 receptor, with IC50= 5 PM.