Errors of drug prescribing.

Seven thousand five hundred and twenty-six prescriptions written for eight hundred and forty patients in three hospital wards have been analysed for errors of drug use and errors of prescription writing. 2. According to the criteria adopted for this survey, more than 3% of prescriptions contained an error of drug use and more than 30% an error of prescription writing. 3. The incidence of adverse drug reactions, overdosage and undertreatment might be reduced by more careful prescribing.