There is limited data about the cardiovascular response to fibreoptic bronchoscopy (FOB) and effects of benzodiazepines and opioids on these changes. Sixty patients were divided into two groups and were premedicated with midazolam-atropine (n=30) or diazepam-atropine (n=30). Patients were then divided into three subgroups, which were given placebo, fentanyl, or alfentanil. Heart rate (HR), systolic and diastolic blood pressures (SBP, DBP) and oxygen saturation (SaO2) values were measured prior to premedication, 3-5 minutes after the administration of placebo or the opioids, and at the passage through the vocal cords, trachea, and carina (VCTC). Beyond the carina, these measurements were obtained every three minutes during FOB and an average value was determined. In the group receiving only diazepam, HR, SBP, DBP increased (p<0.05), whereas when the low-dose opioids were added to diazepam, no significant increase was observed. In the group receiving only midazolam, HR increased significantly only at the level of VCTC (p<0.05). The correlation between the hemodynamic changes and desaturation in the study group was not significant (r= - 0.304). In conclusion, FOB is a procedure in which HR, SAB, and DAB may hse significantly. Midazolam and opioids appear to attenuate the hemodynamic response to FOB.