Objectives: The aim of this study was to compare sedative effects of dexmedetomidine and fentanyl with midazolam and fentanyl in patients undergoing bronchoscopy. Methods: This study was a double-blind randomized clinical trial that was performed on 92 patients who referred to Amir al Momenin Hospital in Arak for bronchoscopy and underwent ASA 1 or 2 underlying grading procedure. Patients were randomly divided into two groups of dexmedetomidine and fentanyl (D) midazolam and fentanyl (M). Primary vital signs including hypertension and arterial oxygen saturation were monitored and recorded. Then, all patients were injected with 2 mu g/kg fentanyl as a painkiller and after 3 min, 30 mu g dexmedetomidine in syringe with code A and midazolam 3 mg in syringe with code B were injected to patients by an anesthesiologist. Then, the two groups were compared in terms of pain at injection, conscious relaxation, satisfaction of operation, recovery time, hypotension, and arterial oxygen saturation and drug side effects and data were analyzed by using statistical tests. Results: There was no significant difference between the two groups in terms of mean age and sex distribution. According to the results of this study, there was no significant difference between the two groups in mean blood pressure (P-value = 0.6) and mean heart rate (P-value = 0.4) at the time of bronchoscopy, but at 5 and 10 min after bronchoscopy, there was a significant difference, mean blood pressure and heart rate were significantly lower in dexmedetomidine group. Conclusion: Both dexmedetomidine and midazolam drug groups contributed to the development of stable and sedative hemodynamics and satisfaction in patients undergoing bronchoscopy, however, the dexmedetomidine and fentanyl group showed a significant decrease in blood pressure and heart rate compared to midazolam and fentanyl and a weaker decrease in arterial oxygen saturation, and patients with bronchoscopy were more satisfied in the dexmedetomidine group.