OBJECTIVES: The cost of remifentanil, a short-acting opiate, is approximately 10 times higher than fentanyl, a longer-acting opiate. Short-acting opiates, however, have the potential to reduce time to extubation (TTE) and may, therefore, decrease length of stay (LOS) and hospital costs. Remifentanil was added to our institution's formulary for use during off-pump bypass surgery. The objective of this analysis was to compare TTE, LOS and total hospital costs between patients who received remifentanil and fentanyl during off-pump bypass surgery. METHODS: The study was prospective and observational in design. Consecutive patients who underwent off-pump cardiac bypass surgery and received either remifentanil or fentanyl from September 1998 to August 1999 were included. Patient charges were converted to costs using cost-to-charge ratios. The percent of patients extubated in the operating room (OR), LOS and hospital costs were compared between the groups. RESULTS: Baseline demographics, including age, female patients, co-morbidities and intraoperative variables were similar between the remifentanil (n=39) and fentanyl (n=20) groups. Patients given remifentanil during surgery were significantly more likely to be extubated in the OR than patients given fentanyl (64% vs. 15%; p<0.001). The mean LOS was similar in both groups (7.3±3.1d vs. 8.3±2.7d; p=0.27). Patients who received remifentanil incurred lower ward ($3,973±1,719 vs. $4,808±1,794; p=0.09), recovery room ($31±40 vs. $65±33; p=0.002) and pulmonary function testing costs ($0±0 vs. $34±103; p=0.045) than patients who received fentanyl. Anesthesia costs were higher among patients who received remifentanil ($476±102 vs. $416±130; p=0.06). Medical and surgical supplies, OR, ICU, cardiac catheterization, laboratory, respiratory therapy, pharmacy, radiology and transfusion costs were similar between the 2 groups (p>0.05). The total cost was $15,272±5,556 and $15,616±4,169 in the remifentanil and fentanyl groups, respectively (p=0.81). CONCLUSION: Remifentanil, when used in off-pump bypass surgery, increases the likelihood of extubation in the OR. However, LOS and total hospital costs remain unchanged.