The technology and terminology of bar codes, the Health Industry Bar Code (HIBC) Standard, issues facing the pharmaceutical industry with respect to bar codes, and potential applications of bar codes in hospital pharmacy are reviewed. Bar codes consist of a series of parallel alternating dark lines and empty spaces. Commonly used bar codes include UPC (Universal Product Code), Interleaved 2 of 5, Codabar, Code 93, Code 128, and Code 39. There are several different types of scanners that may be used for scanning bar codes. Some of the variable features are portability, contact and noncontact, autodiscrimination, and the presence of numeric keypads. The HIBC Council (HIBCC) is a steering committee charged with developing bar-code standards for health care, assigning identification numbers to manufacturers, and providing information to interested individuals. The HIBCC Board includes representatives from health-care providers, equipment manufacturers, drug manufacturers, and wholesalers. Drug manufacturers are concerned about several issues with regard to bar codes; for example, who will pay for the cost of implementation, on what level of packaging will the bar codes be required, and are there legal implications if a poor scan results in patient harm? Bar codes have already been applied in some hospitals for coding blood containers, roentgenogram jackets, medical records, and capital equipment. The potential applications in hospital pharmacy include inventory control, verifying the accuracy of dispensing to both inpatients and outpatients, and record keeping for drug product expiration or disposal. Bar codes also offer pharmacists the ability to perform in-process dispensing controls that are not practical to perform manually. Bar-code technology offers health-care personnel the opportunity to improve work efficiency and increase the accuracy of data entry into automated systems.