Topical betamethasone-17-valerate inhibits the vasodilatation response to local non-pathological heating of rat skin. We have shown that this effect can also be demonstrated in man. Topical betamethasone-17-valerate significantly inhibited the increase in human forearm cutaneous blood flow in response to heat of 44 degrees C, as measured by laser-Doppler velocimetry. This suggests that the effects of topical steroids upon skin blood flow in the rat and in man are similar, and supports the use of the animal model as a paradigm for studying human skin blood flow, and changes in response to anti-inflammatory steroids.