The defined daily dose (DDD) system for use in utilization studies is presented for consideration by pharmacy and therapeutics committee members as an additional tool for drug utilization review and drug regimen review activities. The article describes the development and nature of the DDD system and provides examples of its format, benefits, and limitations. Essentially, the DDD system was devised by the Nordic Council on Medicines, and the early work was done in Norway with the Anatomical Therapeutic Chemical (ATC) diagnostic code system. Whereas consumption andutilization studies in North America have focused on the prescribing by an individual physician and drug utilization for an individual patient, the Scandinavians have attempted a macroscopic focus on the total consumption of drugs for a county or country or other definable political or geographic region. The sale of the drugs is divided by what is agreed on as an average daily dose to yield a unit of measure called the DDD, which is valuable for comparative studies. The DDD system and its component aspects are presented so that hospital pharmacists may evaluate its benefits for potential use in North America.