© 2021 Elsevier Inc.Purpose: This study aimed to evaluate the use of a standard story book, compared to an informative story book, as preoperative preparation to relieve anxiety. Design and methods: A total of 120 children with ASA I-II, aged 6–8 years, scheduled to undergo elective adenoidectomy, tonsillectomy, and adenotonsillectomy were enrolled in this randomized controlled study. The control group received a non-medical, colorful story book, while the intervention group received an informative story book appropriate for their age. The book was either read by literate children or the mothers of illiterate children. The book was read aloud at least once before the surgery while they were together. The patients' baseline anxiety level was assessed using the modified Yale Preoperative Anxiety Scale (mYPAS) immediately after entering the preoperative holding area (T0). Mothers' anxiety level was assessed using the State and Trait Anxiety Inventory (STAI). Information about the reader, how many times the book was read, the age and education level of the mother, and the presence of a surgical history in the patients' siblings was obtained from the mother through a questionnaire. After premedication with oral midazolam, patients' anxiety level was assessed while entering the operation room (T1). Results: The intervention group had significantly lower mYPAS scores at T0 and T1 than the control group. Those who read the intervention book ≥3 times had significantly lower mYPAS values than those who read 2 times or less. Mothers with a low education level had higher anxiety levels in both groups. Conclusions: Repeatedly informing children by reading an informative story book and higher education level of mothers are the most important factors for relieving preoperative anxiety in children. Practice implications: Reducing preoperative anxiety is an important factor for children and their families.