BACKGREOUND: The hemodynamic responses to laryngoscopy and endotracheal intubation, tachycardia and arterial hypertension, are well known and should be minimized. The purpose of this study is comparison of effects of low-dose sufentanil and fentanyl on the changes of blood pressure and heart rate due to laryngoscopy and endotracheal intubation. METHODS: The cardiovascular responses were measured and compared in 60 patients, between 20~65 years old, ASA class I or II, undergoing elective operation pretreated with normal saline (n=20, control group), fentanyl 3 microgram/kg (n=20, fentanyl group), and sufentanil 0.6 microgram/kg (n=20, sufentanil group), respectively. Anesthesia was induced intravenously with pentothal sodium 4~5 mg/kg and endotracheal intubation was conducted after injection of succinylcholine 1 mg/kg. The changes of systolic arterial pressure, mean arterial pressure, diastolic arterial pressure, heart rate, and SpO2 (saturation of arterial oxygen) were measured at postsedation with pentothal sodium, 30 seconds, 1 minute, and 3 minutes following intubation. The variables of each group were compared with preinduction baseline values and fentanyl and sufentanil groups were compared with control group. Data were analyzed for statistical significance using repeated measures of ANOVA (analysis of variance). P<0.05 was considered statistically significant. RESULTS: The systolic and mean arterial pressures at 30 seconds and 1 minute and diastolic arterial pressure at 30 seconds after laryngoscopy and intubation in sufentanil group were significantly lower than values of control group (p<0.01). The heart rates at 30 seconds and 1 minute were significantly attenuated compared with control group (p<0.05). The blood pressures and heart rates of fentanyl group at 30 seconds after intubation were significantly attenuated compared with control group (p<0.05). CONCLUSIONS: The results suggest that pretreatment of fentanyl 3 microgram/kg and sufentanil 0.6 microgram/kg is effective to prevent the elevation of blood pressures and heart rates, and sufentanil 0.6 microgram/kg is more effective than fentanyl 3 microgram/kg to attenuate the hemodynamic changes due to laryngoscopy and intubation.