- The Operating Room (OR) overtime performance depends on two sources of variability. The uncontrollable case-specific variability includes such factors as the patient's characteristics, the type of operation and the surgeon. There is an additional source of variability that arises from the sharing of hospital resources and can be controlled to an extent. Most operational surgery-scheduling approaches determine short-term case schedules in two phases: assignment of cases to ORs and subsequent sequencing decision. In this study, we consider the effect of sequencing decisions on the overtime performance under different surgery start time policies and resource coupling levels. We provide both analytical and numerical results based on a simulation study. Our results conform to the common practice and indicate that scheduling highly variable cases early on leads to better overtime performance. In addition, we conclude that reducing the level of resource coupling across multiple ORs and/or scheduling coupled cases early on significantly reduces overtime. Copyright 2010 Inderscience Enterprises Ltd.