Traditionally, in the studies of the optimal maintenance policies for repairable systems, the nonhomogeneous Poisson process model, which corresponds to the minimal repair process, has been intensively applied. However, in many practical situations, the repair type is not necessarily minimal. In this article, a new repair process based on a new counting process model (so-called the generalized Polya process) is introduced. Then, the issue of the optimal replacement problem is discussed. A bivariate preventive replacement policy is developed and the properties of the optimal policy are studied. Illustrative examples are also presented. In addition, a comparison with a conventional replacement policy is performed.KEYWORDS dependent increments property, generalized Polya process, optimal maintenance policy, stochastic intensity, worse than minimal repair Appl Stochastic Models Bus Ind. 2019;35:637-650.wileyonlinelibrary.com/journal/asmb