To measure hospitalised children's trust in the nurse. Trust is central to the therapeutic relationship between the nurse and the patient. There can be no trusting relationship between the nurse and child if the parents have no trust or block the relationship (Bricher [Journal of Clinical Nursing, 8: 452, 1999]). This study was a cross-sectional, correlational descriptive design using a self-complete questionnaire to measure children's trust in nurses, to examine the relationship between children's trust and their parents, and the correlations between trust and medication adherence, fear and interactions with the nurse. A modified version of the Children's Trust in General Nurses Scale designed by Rotenberg et al. (Journal for Specialists in Pediatric Nursing, 20: 298, 2015) was used. This Scale is a short self-report questionnaire designed to elicit information on children's beliefs in, and attitudes to, trust in nurses. The Strengthening the Reporting of Observational Studies in Epidemiology statement for observational studies was applied (von Elm [British Medical Journal, 335: 806, 2007]). The results indicated high levels of trust beliefs in the nurse. The children's and parents' trust beliefs were found to be correlated. Gender did not influence trust beliefs. Younger children had higher levels of trust than older children, particularly in relation to the perceived honesty of the nurse. Trust beliefs in the nurse lessened with previous exposure to the hospital setting. One-fifth of children reported fear of the nurse. Positive interaction with the nurse was shown to be positively related to adherence to care. Children's level of trust in the nurse can be measured. A trusting child is likely to be less fearful and experience clinical procedures as less threatening and is more likely to adhere to treatment. Children's nurses should recognise that trust can change with age and with multiple hospital admissions. © 2020 John Wiley & Sons Ltd.