Venepuncture and other needle-related procedures can distress children and have a lasting negative impact. Adults’ behaviour during these procedures may affect children’s reactions. However, the literature is contradictory and rarely considers verbal and non-verbal behaviour together. This study therefore examined the effect of adults’ verbal and non-verbal behaviour on children’s distress during venepuncture. Participants comprised 51 child and carer dyads and 10 staff members. Child anxiety was measured before the procedure. The procedure was recorded. The resulting audio-visual data were coded using the Child–Adult Medical Procedure Interaction Scale–Revised. Correlation analysis identified variables that were significantly associated with child distress: child anxiety, carer distress-promoting behaviour, staff distress-promoting behaviour and intimate distance. These were included in a path diagram of child distress. Exploration of the diagram identified that children’s anxiety was mostly strongly associated with children’s distress during venepuncture. Staff and carer behaviour did not increase children’s distress. The results suggest interventions to reduce children’s distress during venepuncture may be more effective if they focus on reducing children’s anxiety beforehand.