We calculated the temperature dependence of the exchange constant between 20 ¿C and 573 ¿C using three previously published data sets from inelastic neutron scattering by spin wave excitations in magnetite. The exchange constant in magnetite varies as a function of temperature approximately as the saturation magnetization to the power 1.7. Our synthesis of temperature dependent spin wave dispersion data provides an experimental foundation for the temperature variation of the exchange energy which is critical for micromagnetic domain structure calculations and for an understanding of the acquisition of thermoremanent magnetization in rocks. ¿ American Geophysical Union 1988