A medication error is a failure in the treatment process that leads to, or has the potential to lead, to harm to the patient.1 Medication errors are a common unfortunate occurrence in hospital. They can occur in different phases of the therapeutic process (prescribing, distribution, administration and monitoring) and have significant impact on morbidity and mortality. Prescribing faults and prescription errors are major problem among medication errors .Prescription errors account for 70 % of medication errors that could potentially result in adverse drug effects.2 Overall it has been estimated prescription errors affect 7 % of medication orders, 2% of patient days and 50 % of hospital admissions.3,4 When harm arises from a medication error it is potentially preventable. The medication errors project was devised to analyze and limit through educational audit and other tools, as much as possible, damages due to the therapeutic process. The project will include 5 phases. Preliminary phase: organizational meetings. Phase I: Patient monitoring: a monitor in collaboration with health professionals of involved units will review all patient charts and will register all adverse drug reactions(ADRs). All ADRs will be introduced by the monitor in a database. Health professional will be invited to send the reports of observed ADRs. Evaluation of ADRs : a panel of experts will evaluate if the ADRs are due to medication errors or not. Phase II :educational audits directed to health professionals will be organized. Tools to reduce the medication errors will be proposed. Phase III: the same procedure of the first phase. Final phase (IV): analysis of data with publication of a scientific article.

Inclusion Criteria:

• all patients hospitalized in the involved units who gave their informed consent. Patients hospitalized during the week-end will be enrolled on the next monday.

Exclusion Criteria:

• all patients with evident mental and physical problems and all patients who did not give their informed consent.

All patients from 18 to 65 and over 65 years old hospitalized in the involved departments during the study period.