The discovery of SP and its potent biological activities have lead to the discovery of other tachykinins and to receptors for them, including the NK1 receptor. Blockade of the NK1 receptor has a number of potentially beneficial effects in medical care including the management of drug-induced emesis and the treatment of depression. The analgesic potential of NK1 receptor antagonists that, in theory, seemed so promising has not met early expectations. However, there is still reason to predict valuable clinical uses for more potent NK1 receptor antagonists in a variety of medical conditions, including FMS.