The focus of this paper is end-to-end reliable transmission in UMTS environment where TCP, a reliable tranport protocol designed to retransmit information in case of loss, is present at the mobile station as well as the wired portion of the network. The mobile and wireless portion of the network, characterized by significant error figures, relies on ARQ to detect and retransmit corrupted frames. In this work, we propose an analytical model for the operation of TCP over ARQ. We investigate several error patterns corresponding to random, slow and fast fading channels. Our results quantify the enhanced performance of TCP over ARQ in terms of throughput as a function of both loss and error.