BEGIN:VCALENDAR PRODID:-//hacksw/handcal//NONSGML v1.0//EN METHOD:PUBLISH BEGIN:VEVENT DESCRIPTION:Medical records come in many forms, including enterprise-wide electronic health records mandated by the 2009 federal stimulus package; lab and clinic-based data management systems; administrative databases for scheduling, billing and inventory control; and secondary databases for clinical research and quality reporting. Making meaningful use of these disparate data sources to improve the cost and quality of patient care turns on our ability to accurately model their complex semantics and exploit these semantics through machine processing. nSince 2003, Cleveland Clinic has applied semantic technologies to making use of diverse data derived from the treatment of over 200,000 patients with cardiovascular disease over the past 30 years. nThis presentation outlines the practical issues and challenges faced, and describes how some of these issues have been overcome while others remain unsolved. nTopics covered include:n