BACKGROUND: Like many healthcare resources, laboratory testing has been over-utilized for years with a huge number of unnecessary lab tests being done. The elimination of unnecessary laboratory testing is becoming more and more important in the control and management of the rapid growth of healthcare costs. OBJECTIVES: To develop a quantitative tool to identify unnecessary laboratory tests, based on quantitative over-utilization, and recommend a plan of control based on results and findings. METHODS: The study used the data warehouse of a tertiary care hospital to extract relevant information about laboratory tests ordered over a specific period of time then used statistical analysis to detect frequency of ordering lab tests to highlight both tests and users who are adding loads to the laboratory testing process and are potential for improvement with different methodologies and approaches. RESULTS: The study identified that more than 11% of ordered tests are repeated, overutilized and simply unnecessary and could be eliminated. 3 tests only; Complete Blood Count, Renal Profile and Blood Glucose constitute 35% of all hospital inpatient lab tests. 10% of ordering physicians were responsible for the actual over-utilization of the lab testing. RECOMMENDATIONS: The study recommended two types of approaches; a user approach and a system approach, where user approach includes different types of orientation, education and training of physicians and other users on the importance and ways of decreasing unnecessary lab test ordering, mainly through avoiding unnecessarily repeated tests, while system approach includes the implementation of different computerized clinical decision support interventions that would help during the order entry process to alert and remind users with the potential of ordering an unnecessarily repeated lab test.