Prospects and problems in fermion-pair production

We discuss 2f production at LC energies (f \neq t). This type of reaction has a big event number and may give interesting hints to the existence and perhaps to details of New Physics like susy, LQ, Z’, etc. {For} any search the radiative corrections have to be controlled carefully. An interesting challenge for theoreticians could also be the Giga-Z option of the TESLA project.