- A system of N non-identical machines in a non-symmetric layout that are maintained by a single repairman is referred to as asymmetric patrolling repairman system. A probability model for a large class of such systems is developed. The model yields useful computational formulae for evaluating system performance measures that include mean down time and availability of a machine, repairman utilization, etc. The so called class admits exponential machine inter-failure times, generally distributed repairman walk times and machine repair times, and a variety of repair scheduling disciplines including most of those that appear in the literature. Many special cases of patrolling repairman systems that belong to this class can thus be examined under one unified model. This is a new result and it offers a common ground for performance comparisons between various systems. 1993.