This volume constitutes the refereed proceedings of the Fourth International Symposium on Formal Techniques in Real-Time and Fault-Tolerant Systems, FTRTFTS '96, held in Uppsala, Sweden, in September 1996. The 22 revised full papers presented were selected from a total of 61 submissions; also included are three invited contributions and five tools demonstrations. The papers are organized in sections on state charts, timed automata, duration calculus, case studies, scheduling, fault tolerance, specification, and verification.