This prize, offered biennially by the Esteve Foundation to the best work on pharmacological research, was awarded this year to Fernando Rodríguez de Fonseca, current Research Director of the Hospital and Foundation Carlos Haya, for the study An anorexic lipid mediator regulated by feeding, published in Nature (2001; 414:209-12). In this work, the main contribution was the discovery of Oleylethanolamide, a hormone that prevents the ingestion of more food than is necessary. The implications of this finding are very important in chronic eating disorders including abnormal satiety and bad regulation of bodyweight –like anorexia.