Transmit diversity techniques have recently emerged as a very powerful tool to mitigate the adverse effect of fading in mobile radio communications. In transmission systems with weak channel coding or slow moving mobiles transmit diversity techniques that can improve uncoded transmission are of particular interest. In this paper we apply a space-time block code (STBC) for channels with intersymbol interference to the EDGE system and compare it to the delay diversity (DD). Simulation results show that STBC outperforms DD in multipath channels.