The objective of this work was to evaluate the effects of ethanol consumption on brown adipose tissue (BAT) thermogenic capacity in mice. Mice offered only ethanol (10%; v/v) for 10 days as drinking fluid had significant reductions in total energy and fluid intakes relative to mice given water, but net weight gains were similar. BAT thermogenic capacity was reduced in mice drinking ethanol, as shown by decreases in tissue protein and succinate dehydrogenase (SDH) activity and in the uncoupling protein content of isolated mitochondria. Ethanol consumption differed greatly between mice offered a choice between ethanol and water for 25 days after a 10-day habituation period, with only ethanol as the drinking solution. Total energy intake of mice that continue to consume the most ethanol voluntarily (up to 25% of total fluid intake) was significantly reduced but carcass fat was increased, relative to mice consuming less or no ethanol. Brown fat thermogenic capacity was not significantly affected by the degree of ethanol consumption. Basal and norepinephrine-stimulated rates of oxygen uptake of isolated brown adipocytes were not affected by ethanol. Thus, changes in the animal capacity for energy expenditure in brown adipose tissue does not appear an important factor to explain the effects of ethanol consumption on fat deposition in mice.