Clinical and Laboratory Standards Institute document AUTO12-A--Specimen Labels: Content and Location, Fonts, and Label Orientation; Approved Standard was developed to reduce the unacceptably high incidence of mislabeled specimens in clinical laboratories. The standard specifies locations and formats for the required human-readable elements that must appear on the label for each clinical laboratory specimen (except labels with limited space, eg, slides and pediatric specimens), a standard label size of 2 x 1 inches (50.8 x 25.4 mm), and an exact required location and format on this label for other commonly used elements. The patient's name is judged to be the single most important element in correct specimen identification and is always to be in the top left corner on each label. The standard also specifies rules for truncation for long patient names, the location and size of the bar code on each label, a list of the most commonly used variable elements that can appear on specimen labels, and the required orientation of labels on specimen tubes.