BACKGROUND: Induction of anesthesia with a high dose of fentanyl and vecuronium decreases the heart rate and blood pressure. This study was designed to evaluate the effect of preinduction atropine on these hemodynamic changes in patients undergoing coronary artery bypass graft surgery (CABG). METHODS: Forty-one patients who underwent CABG were randomly divided into two groups. After insertion of a radial artery cannula and a Swan-Ganz catheter, normal saline 1 ml (control group, n = 20) or atropine 0.5 mg (atropine group, n = 21) was injected intravenously 1 min before the induction of anesthesia. Anesthesia was induced with a first dose of fentanyl (5-8 microgram/kg) and vecuronium (0.12 mg/kg) and a second dose of fentanyl (5-10 microgram/kg). The patient was then intubated. Hemodynamic variables were measured before the induction of anesthesia, 1 min after the administration of each drug during the induction of anesthesia and 5, 10, and 30 min after the intubation. RESULTS: There was no significant differences between the two groups in terms of demographic data except that the number of patients with diabetes mellitus was greater in the control group than in the atropine group. The number of patients treated for hypotension or bradycardia during the induction of anesthesia was greater in the control group than in the atropine group, but this was not statistically significant. Heart rates significantly decreased in the control group but were maintained in the atropine group without any significant tachycardia. Blood pressure significantly decreased in both groups. CONCLUSIONS: Intravenous injection of atropine before anesthetic induction in patients undergoing CABG attenuates the decrease in heart rate resulting from anesthetic induction with high dose fentanyl and vecuronium. However, it didn't prevent the decrease in blood pressure nor did it reduce the incidence of treatment for hypotension.