Brown adipose tissue (BAT) glucagon level was higher in cold-acclimated rats (CA) than in warm controls (WC). Noradrenaline (NA) injection increased BAT glucagon levels in both WC and CA with increases in plasma glucagon levels. The magnitude of increase was significantly greater in CA for plasma glucagon, while it did not differ for BAT between groups. However, BAT glucagon was kept at a higher level in CA after NA injection than in WC.