Summary: This paper considers a combined block and repair limit replacement policy. The policy is defind as follows: (i) The unit is replaced preventively at time \(kT(k=1,2,...)\). (ii) For failures in [(k-1)T,kT) the unit undergoes minimal repair if the estimated repair cost is less than x. Otherwise it is replaced by a new one. The optimal policy is to select T* and x* to minimize the expected cost per unit time for an infinite time span. A numerical example is given to illustrate the method.