Abstract The bremsstrahlung emitted in electron–electron (e–e) and electron–positron (e - –e + ) collisions is investigated. After a short description of the kinematics, cross sections exact to lowest-order perturbation theory are presented and compared with available approximations, and experiments on the two processes are described. The energy losses of electrons and positrons by emission of e–e and electron–positron bremsstrahlung are calculated. The spectra of e–e bremsstrahlung emitted by a hot thermal plasma and the total rate of energy loss due to this process are discussed.