In this paper, we propose a method for designing efficient fail-safe multitolerant systems. A multitolerant system is one that is able to tolerate multiple types of faults, and a fail-safe multitolerant system handles the various fault types in a fail-safe manner. Efficiency issues of interest are fault tolerance-related, and they are: (i) completeness, and (ii) accuracy. Based on earlier work, this paper makes the following contributions: (i) We develop a theory for design of efficient fail-safe multitolerance, (ii) based on the theory, we present a sound and complete algorithm that automates the addition of efficient fail-safe multitolerance, and (iii) we develop the example of an efficient fail-safe multitolerant token ring to show the viability of our approach. Our approach works for finite state systems. © IFIP International Federation for Information Processing 2005.