Young adult flies were submitted to heat shocks (37°C) ofvarious durations (5, 10, 20, 40 or 60 min daily) for 1, 2 or 3 weeks. Aslight longevity increase, in both sexes, was only observed with thelowest heat shock. Longer shocks had neutral or negative effects. Fliessubmitted to the procedure providing a longevity increase did not show adelayed behavioral aging but survived longer at 37°C thancontrol flies. This higher thermotolerance was not associated with anincreased hsp70 induction. The results are discussed in connection withhormesis and previous results showing that hypergravity, an other mildstress, increases longevity and delays behavioral aging: different mildstresses may have contrasting effects on aging and longevity.