Exact calculation of the lowest-order electromagnetic corrections to the processes e/sup +/e/sup -/. --> mu. /sup +/. mu. /sup -/(tau/sup +/tau/sup -/)

Exact expressions for the energy spectrum of the fermions and for the total cross section for the process e/sup +/e/sup -/..-->..f +f /sup -/(..gamma..) in the order ..cap alpha../sup 3/ are obtained in the framework of quantum electrodynamics without neglect of the particle masses.