A basic overview of bar code technology is presented with a focus on applications in the clinical laboratory. Bar codes operate based on symbology, a pattern of bars and white spaces that define alphanumeric characters. The codes are read by scanners, which may be stationary or handheld. Bar codes may be printed using any of several available methods. Bar codes are currently being implemented in several areas of health care, including materials management, clinical laboratory, pharmacy, medical records, and asset management. Planning for implementation of a bar code system is very much like computer installation, in terms of systems analysis and design, procedures, and training. Clinical laboratories should consider use of bar code systems, as they often are faster, better, and more cost-effective than available alternatives.