Background: Sedative and analgesic medications are commonly administered in the Pediatric Intensive Care Unit (PICU) but can cause complications, such as Iatrogenic Withdrawal Syndrome (IWS). The Withdrawal Assessment Tool Version-1 (WAT-1) questionnaire is a validated and reliable diagnostic tool for IWS, but it is not yet available in the Indonesian language. Methods: This observational cross-sectional study was conducted in two phases at Ciptomangukusumo Hospital, Jakarta, Indonesia. The initial phase involved translating the WAT-1 and State Behavioral Scale (SBS) instrument into Indonesian. Subsequently, the validity and reliability of the Indonesian version of WAT-1 were tested on 30 patients who received sedative and analgesic medications for at least five consecutive days in the PICU. Evaluations were performed by two groups of nurses: PICU nurses and training nurses. Results: The Indonesian version of WAT-1 was found to be valid and reliable. The validity showed correlations ranging from good to very strong (r = 0.490 to 0.836) among PICU nurses and strong correlations (r = 0.634 to 0.808) among trained nurses. The WAT-1 questionnaire demonstrated reliability with Cronbach's alpha values of 0.791 for PICU nurses and 0.785 for trained nurses. The Intraclass Correlation Coefficient (ICC) for WAT-1 indicated very good to excellent consistency in assessments, and the ICC for SBS indicated excellent consistency. Conclusion: The Indonesian version of WAT-1 and SBS is a valid and reliable diagnostic tool for detecting Iatrogenic Withdrawal Syndrome in Children. © 2024 The Author(s). Published by Bentham Open.