We consider the reliability proble of the SM/PH/1 queue with repairable server of PH life time and PH repai time. The generalizedservices are proved to be dependent on each other and not to have the same distribution if the system is at transient stata For this reason the transient behavior of the system is so complex that we can not give any available results On the contrary the repairable queueing system is shown to be equivalent to the classical SMSM(PH)/1 queue when the system is at steady state, where SM(PH) denoted Markovian semi-Markov process which was discussed in Latouche [10] and Sengupta [23] By means of the equivalent model SM/SM(PH)/1 the explicit expressions of the reliability quantities are derived, for instance, the steady state availability and the steady state failure frequency Copyright1999IFAC