Aim Polypharmacy exists in children and young people (CYP), generates clinician concern and a desire to undertake deprescribing, tempered by concerns about parental acceptability. The aim of this study was to validate and apply a questionnaire to assess the attitudes of CYP and their parents/guardians towards polypharmacy and deprescribing. Methods A paediatric version of the Revised Patient Attitudes Towards Deprescribing (rPATD) was developed – the Child and Parent Attitudes Towards Deprescribing (CHATD) questionnaire. Validation steps included: Content evaluation panel, face validity (piloting), factor analysis, internal reliability and test re-test reliability. Participants were prospectively recruited from three UK paediatric hospitals. The questionnaire includes two global questions and four factors concerning participants medications: burden, appropriateness, concerns about stopping, and involvement. Results 216 participant responses were analysed (149 parents, 67 CYP). Factor analysis showed the CHATD questionnaire aligned well with the underlying structure of the rPATD with good internal reliability and test-retest reliability. In comparison to their parents, CYP felt their medications were more burdensome (3.0 vs 2.4, p=0.003), less appropriate (3.6 vs 4.2 p=0.008) and wanted and experienced less involvement (3.8 vs 4.8 p<0.001). Most parents (70%) and 55% of CYPs were happy to have a medication deprescribed if the doctor agreed. Conclusions The CHATD questionnaire is a valid, reliable tool for assessing deprescribing attitudes among children, young people, and parents. Whilst CYP and their parents showed some concern over the stopping of their medications, most parents and CYP were willing to have a medication deprescribed under the guidance of their doctor.