Effects of prostaglandin E 2 (PGE 1) were examined on the oxygen consumption and intracellular calcium concentration of rat brown adipose tissue (BAT). PGE 2 0.1 nM-1 μM increased oxygen consumption of the tissue blocks of BAT, with a maximum 2–13 min after PGE2 administration. PGE 2 was most effective at 1 and 10 nM, and the oxygen consumption was elevated for over 40 min. Pretreatment of BAT with indomethacin, a prostaglandin synthesis inhibitor, did not affect the increase in oxygen consumption induced by noradrenaline. PGE 2 at 1–10 nM gradually increased the intracellular calcium concentration of freshly dispersed single brown adipocytes by 3–4 times in 30 min. PGE 2 also increased the intracellular calcium concentration of brown adipocytes in calcium-free medium. These results raise the possibility that PGE 2 and noradrenaline affect heat genesis and metabolism of BAT independently.