ICI D7114 is a selective beta 3-agonist which stimulates brown adipose tissue thermogenesis. In the present study the effects of 18 days treatment with ICI D7114 (2 mg/kg/day orally) on macronutrient selection and brown adipose tissue thermogenesis were investigated in Sprague-Dawley rats. The rats were maintained on a free-feeding self-selection paradigm with three pure macronutrient diets of carbohydrate, fat and protein. Treatment with ICI D7114 did not change the macronutrient selection or total calories consumed by the rats. To monitor the thermogenic activation of brown adipose tissue the binding of [3H]GDP to brown adipose tissue mitochondria was measured. The treatment with ICI D7114 increased the binding of GDP both when expressed as total binding per lobe (P < 0.001) and per mg of protein (P < 0.01). It is concluded that ICI D7114, used in doses affecting brown adipose tissue thermogenesis, does not change the macronutrient selection or total energy intake in Sprague-Dawley rats.