Complex reliability systems have an important role in sophisticated systems like mass communication and computer-aided networks. Optimization methods for these systems thus have a large scope and potential. A procedure leading to the optimal (n, m, N*) series parallel systems with provision for a fixed repair facility is developed. The three entries respectively denote the fixed repair‐stage n, the number of units in the series m, and the optimal number of parallel units N* in the system. Under certain conditions and based on minimal cost considerations, the optimal N* is obtained. An illustration, specializing to a negative exponential law governing the stochastic failures, is provided.