This study evaluated the impact of clinical pharmacist-led interventions on medication errors and preventable adverse drug events among patients in the ICU. The clinical pharmacist performed medication chart review, patient monitoring, and attended medical rounds in order to evaluate the appropriateness of the pharmacological treatment, identify and report drug-related issues, and provide evidence-based recommendations for the management of medication errors. When the pharmacist’s recommendations were implemented by prescribing physicians, approximately half of medication errors were intercepted before reaching the patient, resulting in fewer preventable adverse drug events.