beta 3-adrenoceptors have been described through both molecular and pharmacological studies. In this context, it has been characterized the beta 3-adrenoceptor agonist activity of a new compound (Trecadrine), and evaluated whether it exhibits additional activity at beta 1- and beta 2-adrenoceptor subtypes. In addition, it has been tested its potential anti-diabetic properties in a model of alloxan-induced diabetes in rats. Our data show that Trecadrine induces oesophageal muscularis mucosae relaxation, indicating a putative action on beta 3-adrenoceptors. In the absence of beta 3-adrenoceptor antagonists, assays with beta 1- and beta 2-adrenergic antagonists reveal a quite remarkable selectivity for beta 3-adrenoceptors. Furthermore, it has been suggested that this molecule has hypoglycaemic and lipomobilizing effects, although hypoglycaemia was not related to an increase in insulin secretion in diabetic rats. It is concluded that Trecadrine mainly acts through beta 3-adrenoceptors, and it may constitute a potential drug in the treatment of diabetes.