Systems’ performance declines after successive usage, hence proper and adequate maintenance is required to prolong its operational duration. In this paper the performance of a repairable system subjected to several modes of failure is examined. A repairable system is defined as a system which, after failing to perform one or more of its functions satisfactorily, could be restored to a satisfactory performance by a method other than replacement of the entire system. Systems upon failure are perfectly, minimally, or imperfectly repaired. In Imperfect repair, the system performance is weakened after each repair and thus it fails more frequently. This article addresses the case where a repairable system is exposed to multiple failure modes with imperfect repair.  The performance of the system is measured using availability, hence, a closed analytical form expression is derived for the long term probability the system being in the operational state under exponentially distributed times between failures and repair times.