This paper presents a case study of implementing lean principles and statistical analysis to improve operating rooms (ORs) performance measures, i.e., block utilization and turnover time. Eight-step problem solving process was applied to identify wastes and their associated root causes and recommend solutions to improve the OR performance. The study was carried out at a tertiary hospital in Pennsylvania. The analysis has identified the main reasons of delays that impact performance, i.e., waiting in OR after surgery due to bed unavailability, delays in preoperative process due to IV insertion difficulty and unavailable beds, and scheduling problems such as late first case starts and unrealistic surgery schedules. Countermeasures were developed. Reevaluating the current scheduling practice and developing a scheduling tool are believed to be the best countermeasures in terms of ease of implementation and impact.