To investigate the effects of hyperthermia and facial fanning during hyperthermia on hand-grip exercise performance and thermoregulatory response, we studied eight male subjects, aged 20-53 years. Subjects exercised at 20% of maximal hand-grip strength in the sitting position under three conditions: normothermia (NT), hyperthermia without fanning (HT-nf) or with fanning at 5.5 m X sec-1 wind speed (HT-f). Hyperthermia (0.5 degrees C higher oesophageal temperature than in NT) was induced by leg immersion in water at 42 degrees C. Mean exercise performance was markedly reduced from 716 contractions (NT) to 310 (HT-nf) by hyperthermia (P less than 0.01) and significantly (P less than 0.05) improved to 431 (HT-f) by facial fanning. Hyperthermic exercise was accompanied by significant increases in forearm blood flow (71%) and the local sweat rate on the thigh (136%) at the end of exercise compared with that in NT. Heart rate (HR) and rating of perceived exertion (RPE) increased during exercise and were higher in HT-nf than in NT at any given time of exercise. Oesophageal, tympanic (Tty) and mean skin temperatures were also significantly higher in HT-nf than in NT. Facial fanning caused a marked decrease in forehead skin temperature (1.5-2.0 degrees C) and a slight decrease in Tty, HR and PRE compared with that in HT-nf at any given time of exercise. These results suggested that hyperthermia increased thermoregulatory demands and reduced exercise performance. Facial fanning caused decreases in face skin and brain temperatures, and improved performance.