Turbo decoding structures which are used in wireless communication systems are highly complex. In order to reduce decoding complexity, Zigzag codes, a class of error-correcting codes, are developed. A concatenated Zigzag encoder has several encoders connected by several interleavers. The interleaver performs permutation of the input data sequence. In this study, we have investigated performance of concatenated Zigzag code with/without interleaver in additive white Gaussian noise and Flat fading channels. Simulation results show that the proposed random interleaver can significantly improve bit-error-rate performance.