OBJECTIVES: Large antimicrobial consumption in intensive care units (ICUs) contributes heavy health care burden in Taiwan. This study evaluates the short term influence of pharmacist-led antimicrobial stewardship (PLAS) in ICUs. METHODS: A prospective PLAS program was implemented in medical and surgical ICUs, including dose optimization (renal dose monitoring and therapeutic drug monitoring), streamlining or de-escalation of therapy, antimicrobial order forms, and antimicrobial treatment duration review, which any antimicrobial duration over 7days was reviewed. Data collection was from October 19, 2011 to December 2, 2011. Patients who admitted to ICU and received at least one parenteral antimicrobial were included. Outcomes included suggestion implementation rate of pharmacist interventions and cost that saving from dose optimization. Feedbacks of non-accepted suggestions were also addressed. RESULTS: Sixty-two (21%) of study population received 88 suggestions. Sixty-two (70.5%) suggestions were implemented. The majority of suggestions is duration review (30.7%) followed by streamlining or de-escalation of therapy (30.6%) and dose optimization (27.3%). There was 76,238 NTDs saving from renal dose monitoring. Further efforts we can make are found from reasons of non-accepted suggestion. For example, education on prophylactic antibiotics and antimicrobial renal dosage adjustment should be provided. Since, we found that prolonged (>3days) post-operation antimicrobial prophylaxis until inserted drainage lumen removed and refusing dose increasing because impaired renal function was expected by doctors. Involvement in multidisciplinary specialists is required due to denials from no recommendation from infectious disease physicians. CONCLUSIONS: A PLAS efforts rationale antimicrobial utilization and leads to potential reduction in both the incidence of adverse effects and the burden of health care. Through feedback from refused suggestion, however, we found that antimicrobial stewardship should include a multidisciplinary team, especially incorporating with infectious disease physicians.