OBJECTIVE: While there is raising awareness of pharmacists’ contribution in a critical care team, little is known about its economic, clinical and humanistic outcomes. The aim of this study is to assess the economic-based impacts of pharmacists’ intervention in a medical intensive care unit (MICU) in a medical center in Taiwan. METHODS:  It was hypothesized that a clinical pharmacist’s provision of pharmaceutical care in an MICU from October to December in 2005 (i.e., intervention group) would result in a reduction of patients’ average drug expenditures and their length of stay (LOS) as compared to those patients with partial pharmacists’ intervention in the same unit in the same time period in year 2004 (i.e., historical control group).  Independent t test was performed to investigate difference of drug expenditures and LOS. RESULTS:  There is no statistically significant difference of average drug expenditures and LOS between two groups other than having comparable patient characteristics (e.g., ages, genders, bed occupancy rates, APACH II scores of admission to and discharging from the MICU), and their professional caregivers’ characteristics (i.e., seniority of attending physicians and nurses).  However, with pharmacist’s provision of pharmaceutical care in MICU, there was an average of $27 per patient daily savings of drug expenses and a reduction of 0.67 day of LOS in MICU, which may reduce the cost by $205 per patient per admission. CONCLUSIONS: While pharmacists’ involvement have been improving the quality of medical services and patients’ medication use, our study further explores pharmacists’ contribution in a medical critical care team. Health policy makers and administrators in hospitals should not underestimate the importance of pharmacists’ roles in evaluating medical economic benefits.