The American Pharmacists Association defines drug compounding as the mixing of ingredients, including dilution, admixture (mixing of medications), repackaging, reconstitution, and other manipulations of sterile products, to prepare a medication for patient use. Many institutions recommend that sterile medications should be prepared by the pharmacy, unless it is an emergency situation. The administration of the final compounded products must begin within 1 hour of preparation. The operating room is a medication-intensive setting. It is important to establish safety processes on and off the sterile field to prevent medication errors. Medication errors in the United States have affected at least 7 million people every year, resulting in 7,000 to 9,000 deaths in the United States annually. This chapter helps the reader to learn about: preparing medications; transferring medications onto the sterile field; handling and administering medications on the sterile field; disposing of medications; and handling of chemotherapy agents.