The short-tailed shrew Blarina brevicauda is one of the red-toothed shrews of the subfamily Soricinae. The thermogenic capabilities of B. brevicauda were examined to see whether the relatively high BMR, which is characteristic of this group, was reflected in enhanced thermogenic abilities in the face of severe cold stress. A helium-oxygen environment was used to mimic severe cold. Our results confirmed the relatively high BMR. This was 17.8 W·kg−1, which is approximately double comparable values calculated from allometric equations for placentals. The maximum increase in sustained heat production of warm acclimated shrews was four to five times their BMR, but this was eight to nine times "expected" placental values. Cold acclimation had a marked effect on the thermogenic capacity of B. brevicauda. Summit metabolism was increased by some 50% to a level of 108 W·kg−1 or 41 W·kg−0.75. Such values are considerably higher than those reported for most small mammals and explain the shrew's winter activity in Holarctic regions.