Tachykinin receptor subtypes were initially defined using agonist potency ratios for the endogenous ligands substance P (SP), neurokinin (NK) A, and NKB. On this basis it was suggested that there are three tachykinin receptor subtypes. These subtypes were designated NK1, NK2, and NK3, where SP is most potent at NK1receptors, NKA is most potent at NK2receptors, and NKB is most potent at NK3receptors. Recently analogs of the endogenous ligands that show greater selectivity (about 1000-fold) for the different receptor subtypes have been developed. In addition selective antagonists, which are either nonpeptides or modified peptides, for the receptor subtypes have been developed. This minireview concentrates on the wealth of new knowledge concerning the tachykinin receptor subtypes subserving bronchoconstriction in several mammalian species, including man, provided by the use of these selective agonists and antagonists.Key words: neurokinins, bronchoconstriction, substance P, neurokinin A, receptor subtypes.