One of the major causes of medication errors is the ongoing use of potentially dangerous abbreviations and dose expressions. Underlying factors contributing to many of these errors are illegible or confusing handwriting by clinicians and the failure of health care providers to communicate clearly with one another. Because medication safety and the identification, prevention and timely reporting of medication errors are of primary importance to the Joint Commission, this issue of Sentinel Event Alert specifically addresses medication errors related to the use of dangerous abbreviations and dose expressions used in prescribing medications.