In this paper we propose a new two-way relaying scheme using a quantize-and-forward strategy with space-time block coding (STBC). In this scheme two nodes use STBC to simultaneously transmit their signals to the relay. At the relay these signals are estimated by using minimum mean square error ordered successive interference cancellation and then are quantized to the nearest signal constellation point. The relay linearly combines the quantized signals and broadcasts the combined signal to both nodes using a STBC. The performance of the proposed scheme is evaluated numerically in an uncorrelated flat fading channel and compared to a space division duplex reference scheme. We also investigate the effect of power-splitting on the performance of the scheme.