OBJECTIVES: Collecting information on patterns of drug prescriptions and on factors influencing prescribing decisions is fundamental for supporting the rational use of drugs. This study was aimed at investigating patterns of drug prescription in paediatric outpatients and at evaluating determinants of prescriptions for respiratory tract infections (RTIs). METHODS: We conducted a national cross-sectional survey involving primary care paediatricians and parents. Diagnoses and prescriptions made at each consultation were described. Poisson regression models were used to analyse determinants of drug and antibiotic prescriptions for visits due to RTIs. RESULTS: A total of 4,302 physician and parent questionnaires were analysed. These corresponded to 2,151 visits, 792 of which were due to RTIs. Drugs were prescribed in 83.4% of RTI visits, while antibiotics were prescribed in 40.4%. According to paediatricians' perceptions, 84.2% of parents of children with a RTI expected to receive a drug prescription. Paediatricians' perception of parental expectations was the strongest determinant for prescription of drugs and specifically of antibiotics [adjusted relative risk (RR): 1.7 and 3.6, respectively; P < 0.001]. However, in 77.1% of RTI visits, paediatricians judged themselves as not being influenced at all by parents' expectations in their decision to prescribe. CONCLUSIONS: This study underscores that relational factors, in particular perceived parental expectations, are one of the leading factors of drug prescriptions in paediatric ambulatory care settings, reinforcing the opinion that communication between physicians and parents can affect prescription patterns.