Dexmedetomidine is a pharmacological option for sedation in children. In this study, the efficacy of intranasal dexmedetomidine to reduce preoperative anxiety in pediatric patients is compared with that of oral midazolam. A prospective, randomized, double-blind, controlled trial was conducted on children 2-12 years of age, randomly assigned to one of the following two groups: group A received premedication with oral midazolam and intranasal placebo, group B received intranasal dexmedetomidine and oral placebo. Anxiety was assessed with the modified Yale scale, and a risk analysis and number needed to treat was performed. A total of 108 patients were included, 52 (48.1%) treated with dexmedetomidine, and 56 (51.9%) with midazolam. Anxiety was less frequent in the dexmedetomidine group at 60minutes (P=.001), induction (p=.04), and recovery (P=.0001). Risk analysis showed that dexmedetomidine reduced the risk of anxiety by 28% (RAR=0.28, 95% CI; 0.12 to 0.43) and to prevent one case of anxiety, four patients need to be treated with intranasal dexmedetomidine (NNT=4, 95% CI: 3-9).Changes in heart rate, mean arterial pressure, and oxygen saturation, were statistically significant in the dexmedetomidine group, with no clinical consequences. There were no cases of bradycardia, hypotension or oxygen desaturation. Intranasal dexmedetomidine premedication is more effective than oral midazolam to reduce preoperative anxiety in pediatric patients. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.