Ergotamine was shown to inhibit the binding of radiolabelled CCK to both CCK-A and CCK-B receptors with a relatively modest potency (IC50 = 30 μM and 17 μM respectively). The hormone Cholecystokinin (CCK) is currently the object of much interest. It plays an important role in the control of pancreatic and biliary secretion, and of intestinal motility. It is also widely distributed in the CNS, and CCK antagonists have been shown to be anxiolytic in several animal models.1 A major advance in the development of non-peptide CCK ligands was the discovery of mould metabolite asperlicin, and its affinity for the CCK receptor.2 This lead gave rise to a number of highly potent CCK antagonists based on the benzodiazepine skeleton3 and, more recently, to a series of quinazolinone-based compounds.4 A mould metabolite which has received far less attention in this context is ergotamine. It has been suggested that ergotamine mimics the active conformation of CCK.5 This hypothesis was based on pharmacological similarities and the identification of some structural elements common to both compounds. No binding data was available at that time.6 We felt that it was important to demonstrate a specific interaction between ergotamine and the CCK receptor as a first step in the exploitation of this potential lead, and we report here the results of this study.