Propofol is commonly used IV anesthetic, it has been formulated in a concentration of 10 mg/ml in a fat emulsion consisting of 10% soybean oil (long-chain triglycerides). When used for anesthetic induction, propofol causes pain on injection in 28%-90% of patients. pain probably results from a direct irritant effect. Several methods have been used to reduce this pain. Lidocaine pretreatment has been commonly proposed to decrease propofol induced pain, but its failure rate is between 13-32%. Dexmedetomidine is highly selective alfa-2 adrenoreceptor agonist. Alpha-2 receptors are located on blood vessels where they inhibit norepinephrine release. Investigators, therefore, speculated that dexmedetomidine could attenuate the pain due to injection of propofol. Investigators conducted a study to determine the efficacy of dexmedetomidine in decreasing pain due to injection of propofol.