A technique for designing totally self-checking (TSC) FCMOS (Fully Complementary MOS) designs for multiple faults is presented in this paper. The existing techniques for self checking design consider only single faults, and suffer from high silicon area overhead. The multiple faults considered in this paper are multiple breaks, multiple transistors stuck-offs and multiple transistors stuck-ons. Starting from FCMOS design, small modifications (addition of two-weak transistors) make the original circuit totally self-checking. Experiemntal results show the overhead, delay and power consumption for the proposed technique. This paper also presents a technique for designing multistage TSC FCMOS circuits.