General turbo codes have an excellent bit-error-rate (BER) performance at low signal-to-noise ratios (SNR) in additive white Gaussian noise (AWGN) channels. However, the standard turbo decoding algorithm is highly complex. To reduce its decoding computational complexity, zigzag codes are currently used. A zigzag code is a family of error-correcting codes similar to the single parity check codes. It is an important issue, how the segment length called J and the interleaver can affect concatenated zigzag code performance. In this study, the segment size and interleaver structure are investigated in order to obtain a high bit-error-rate performance for the concatenated zigzag code with four encoders and three random interleavers. Realized computer simulation results are compared with/without interleaver for various values of J over a noisy channel.