Abstract: The performance of turbo codes on frequency non-selective slow Rayleigh fading channels is investigated in this paper. The turbo decoder which performs maximum-likelihood(ML) decoding using the modified Euclidean distance metric and channel state information is considered. Based on the union bound and code weight distributions, the exact upper limit of turbo codes performance on fully interleaved Rayleigh fading channel is derived. A efficient tool for the design and analysis of turbo codes on Rayleigh fading channels is presented.