The aim of this randomized double-blind clinical trial is to evaluate and comparison the hemodynamic changes of two regimens propofol + ketamine and thiopental Na + ketamine with etomidate during anesthesia induction. A total of 120 patients, meeting eligibility criteria, were randomly allocated into three equal groups. Inclusion criteria are informed written consent; ASA class Ι-ΙΙ; Age between 18 and 45 years; Elective surgery. Exclusion criteria are Adrenal insufficiency; Received etomidate or propofol or thiopental in one week ago; Receiving steroids at 6 months ago; Sensitivity to etomidate or propofol or thiopental; Egg and soy allergy; Sepsis; endocarditis; Chronic inflammatory diseases; Any severe disease and seriously endocrine, neurological, Psychiatric and Metabolic disorders; Pregnant or lactating women; Need for rapid intubation in emergency patients; Asthma; HIV infection; History of hypertension; Taking beta blocker, calcium blockers and angiotensin II inhibitors. After establishing routine monitors, blood pressure (systole, diastole and mean arterial pressure) and heart rate are measured and serve as baseline values. At first, all patients will receive 0.02 mg/kg midazolam and 2 µg/kg fentanyl. One minute later anesthesia induces according to the following regimen; group A: Normal saline + 0.3 mg/kg Etomidate, group B: 0.5 mg/kg Ketamine + 1.5 mg/kg Propofol, group C: 0.5 mg/kg Ketamine + 3 mg/kg thiopental Na. Immediately after the prescribed hypnotic drug, 1.5 mg/kg succinylcholine for muscle relaxation and ease of intubation will be used. 1 min after administration of hypnotic drugs just before laryngoscopy as well as 1 and 3 min after laryngoscopy and tracheal intubation, blood pressure and heart rate will be measured and compared in three groups.