Hormonal stress response due to manipulation of the upper and lower respiratory tracts occurring during rigid bronchoscopy represents a potentially great hazard to safeanesthesia.There were many attempts to attenuate these adverse effects.Dexmedetomidine is highly selective, short-acting central alpha 2 agonist. It has increasingly gained popularity among anesthesiologists as adjuvant to general and regional anesthesia techniques. This study was conducted to compare the efficacy of administrating fentanyl, dexmedetomidine or lidocaine on control of hormonal changes in response to rigid bronchoscopy in pediatric patients. Ninety ASA I-II children aged 2-12 year were randomly assigned to 3 groups: fentanyl (F), dexmedetomidine (D) and lidocaine (Z). cortisol, ACTH and vasopressinlevels were measured and recorded. Results revealed that patients in the D group showed less elevation of ACTH levels in in response to the insertion of the rigid bronchoscope compared with the other groups, cortisol levels increased significantly after bronchoscopy in the lidocaine group, meanwhile, changes in vasopressin levels were not significant between the groups We concluded that dexmedetomidine can be used safely and effectively to attenuate the hormonal responses to rigid bronchoscopy in pediatric patients.