The effects of thermal annealing (from 25°C to 300°C ) on exchange-coupling fields in NiFe/FeMn films were investigated. The exchange-coupling fields decrease with an increase in the temperature from 90°C to 210°C but remain constant at 210°C or higher in Ta/NiFe/FeMn films with a Ta underlayer. However, the exchange-coupling fields in these annealed Ta/NiFe/FeMn films make a dramatic recovery if the FeMn layers are thinned by ion-milling and annealed again at 210°C or higher. These changes in the exchange-coupling fields are explained as thermal fluctuations in FeMn spins. On the other hand, the exchangecoupling fields increase at 210°C or higher in NiFe/FeMn films without Ta underlayers. XPS depth-profile results reveal interdiffusion in the NiFe-FeMn interface after annealing at higher than 210°C in the NiFe/FeMn films.