Several studies have shown the efficacy of psychological interventions in reducing preoperative anxiety in children undergoing surgery. This study aims to investigate the effectiveness of a specific non-pharmacological technique, the relaxation-guided imagery, in reducing both preoperative anxiety and postoperative pain in a sample of 60 children (6-12 years old) undergoing minor surgery who were randomly assigned to the experimental group (N = 30) or the control group (N = 30). The first group received the relaxation-guided imagery, before the induction of general anesthesia; the second group received standard care. The levels of preoperative anxiety and postoperative pain were assessed using, respectively, the modified Yale Preoperative Anxiety Scale and the Face, Legs, Activity, Cry, and Consolability Scale. The results showed a statistically significant difference between groups, with less anxiety and less pain for children included in the experimental group (p < .001; p < .001).Conclusion: Results suggest that relaxation-guided imagery reduces preoperative anxiety and postoperative pain in children. Future studies should focus on developing protocols and studying the eventual reduction of administered drugs for anesthesia and pain. What is Known: • Literature suggests the usefulness of relaxation-guided imagery in reducing anxiety and pain in the perioperative period. • Stronger evidences are needed to support the application of relaxation-guided imagery as routine care in pediatric surgery. What is New: • To our knowledge, this is the first randomized study to investigate the efficacy of relaxation-guided imagery in reducing preoperative anxiety and postoperative pain within a single pediatric sample. • The present study provides stronger evidence in an area that is lacking in research.