Clinical pharmacists rarely are involved in the selection and dosing of anesthetic agents. However, when practicing evidence-based medicine in a cost-conscious health care system, optimizing drug therapy is imperative in all areas. Thus, we provide general information on anesthesiology, including the different types of breathing systems and the components of anesthesia machines. Modern inhalation anesthetics that are predominantly used in clinical practice include one gas--nitrous oxide--and new volatile liquid agents--isoflurane, desflurane, and sevoflurane. Desflurane and sevoflurane are the low-soluble inhalation anesthetics, and they offer some clinical advantages over isoflurane, such as fast induction and faster recovery with long procedures. However, efficient use of isoflurane can match the speed of induction and recovery of the other agents in certain cases. In addition, the patient characteristics, duration and type of procedure, type of breathing system, and efficiency in monitoring must be considered when selecting the most optimal therapy for each patient. Maximizing the clinical advantages of these agents while minimizing the waste of an institution's operating room and pharmacy budget requires an understanding of the characteristics, pharmacokinetics, and pharmacodynamics of these anesthetic agents and the collaborated effort from both the anesthesia and pharmacy departments. An anesthetic agent algorithm is provided as a sample decision-process tree for selecting among isoflurane, desflurane, and sevoflurane.