Abstract The influence of artificially induced anaemia on thermal strain was evaluated in trained males. Heat stress trials (38.6C, water vapour pressure 2.74kPa) performed at the same absolute work rates [20min of seated rest, 20min of cycling at 30% peak aerobic power (VO2peak), and 20min cycling at 45% VO2peak] were completed before (HST1) and 35days after 3 units of whole blood were withdrawn (HST2). Mild anaemia did not elevate thermal strain between trials, with auditory canal temperatures terminating at 38.5C [(0.16), HST1] and 38.6C [(0.13), HST2; P0.05]. Given that blood withdrawal reduced aerobic power by 16%, this observation deviates from the close association often observed between core temperature and relative exercise intensity. During HST2, the absolute and integrated forearm sweat rate (msw) exceeded control levels during exercise (P0.05), while a suppression of forehead msw occurred (P0.05). These observations are consistent with a possible peripheral redistribution of sweat secretion. It was concluded that this level of artificially induced anaemia did not impact upon heat strain during a 60-min heat stress test.