The basic concepts of stationary Markov processes and particularly their application to transmission system reliability evaluation are discussed and illustrated. Transmission components are assumed to operate within a 2-state fluctuating environment described by normal and stormy weather conditions. Markov processes are used to determine the system failure rate and the probabilities of failure for simple configurations and to illustrate the bunching effect of storm associated failures on parallel facilities. The variation in the failure probabilities is shown as a function of the expected repair time and the degree of storm associated failures. The results are compared with those obtained using a previously published approximate method.