Abstract Background We previously developed proxy indicators (PIs) that can be used to estimate the appropriateness of medications used for infectious diseases (in particular antibiotics) in primary care, based on routine reimbursement data that do not include clinical indications. Objectives To: (i) select the PIs that are relevant for children and estimate current appropriateness of medications used for infectious diseases by French paediatricians and its variability while using these PIs; (ii) assess the clinimetric properties of these PIs using a large regional reimbursement database; and (iii) compare performance scores for each PI between paediatricians and GPs in the paediatric population. Methods For all individuals living in north-eastern France, a cross-sectional observational study was performed analysing National Health Insurance data (available at prescriber and patient levels) regarding antibiotics prescribed by their paediatricians in 2017. We measured performance scores of the PIs, and we tested their clinimetric properties, i.e. measurability, applicability and room for improvement. Results We included 116 paediatricians who prescribed a total of 44 146 antibiotic treatments in 2017. For all four selected PIs (seasonal variation of total antibiotic use, amoxicillin/second-line antibiotics ratio, co-prescription of anti-inflammatory drugs and antibiotics), we found large variations between paediatricians. Regarding clinimetric properties, all PIs were measurable and applicable, and showed high improvement potential. Performance scores did not differ between these 116 paediatricians and 3087 GPs. Conclusions This set of four proxy indicators might be used to estimate appropriateness of prescribing in children in an automated way within antibiotic stewardship programmes.