Body temperature, blubber thickness and lung capacity (Ve) were recorded in newly killed minke whales, while respiratory frequency (f) was determined in free-swimming animals. Mean deep (thoracic) body temperature was 34.7±0.8 (SD) °C (n= 14). Weighted mean core/blubber interface temperature in animals caught in 2.5-5.5 °C water was 28.8±1.7 °C (n= 8). The minimum average rate of sensible heat loss (HLs) was 3.81±0.53 (SD) W kgw-0.75 (n= 8) in animals with body masses (w) in the range of 1840 to 5740 kg, HLs being inversely proportional to ω (HLS= - 2.98 10-4 w + 4.89 W kgω-0 75 (n= 8, r-2= 0.73, P < 0.01)). The average rate of respiratory heat loss (HLr) was 0.26±0.04 (SD) W kgw-0.75, regardless of w, in the same 8 animals. Total rates of heat loss (HL=HLr+HLs) in 2.5-5.5 °C water ranged between 3.40 and 4.87 W kgw-0.75, with an average of 4.06±0.52 (SD) W kgw-0.75 (n= 8). Estimates of oxygen consumption based on records of f and Vc and data on oxygen extraction from other cetaceans, yielded a range of metabolic rates which compared nicely with the calculated HL values.