Handwashing is generally considered the most important procedure in preventing nosocomial infections, because many types of these infections may be caused by organisms transmitted on the hands of personnel. Personnel should wash their hands before and after significant contact with any patient. The risk of personnel acquiring transient hand carriage of organisms is usually greatest after contact with excretions, secretions, or blood; patients at greatest risk are those undergoing surgery, those with catheters, and newborn infants. Although handwashing with an antiseptic agent between patient contacts is theoretically desirable, handwashing with soap, water, and mechanical friction are sufficient ro remove most transiently acquired organisms. Antiseptic agents may produce excessively dry skin if used frequently, and any regimen of handwashing that leads to dermatitis negates the purpose of handwashing. We favor antiseptics for handwashing before surgery and other high-risk invasive procedures and in the care of newborn infants but prefer soap and water for other handwashing.