Tetrapeptide amides of the formula ##STR1## wherein R.sup.1, R.sup.2, R.sup.3, A and B represent certain specified substituent groups and where n is 2-5, p is 1-5 and r is 1 or 2. The compounds exhibit pharmacological activity when tested in the transmurally stimulating guinea pig ileum preparation indicating their affinity for opiate receptor sites and they may therefore be used in man for those conditions where an opiate-like effect is indicated.