Anxiety disorders are highly prevalent in children with asthma yet very little is known about the cognitive and parent factors that may underpin this relationship. The present study investigated interpretation biases in children with asthma and anxiety and their parents, and whether parent-child discussions influenced children's interpretations. Eighty-nine parent-child dyads were included across four groups: children with asthma and anxiety, children with anxiety only, children with asthma only and healthy children (aged between 8 and 13 years old). Interpretation bias was assessed using ambiguous scenarios. Children with anxiety showed an interpretation bias in the general threat scenarios, whereas children with asthma showed an interpretation bias in the asthma threat scenarios. Parental predictions of their child's responses showed similar results. Parent-child discussions increased avoidance for children with anxiety and no asthma across all scenarios, but only for children with asthma and anxiety in the asthma threat scenarios. The results provide partial support for a cognitive theory of asthma and anxiety in children and suggest that parents play a role in influencing children's thinking styles. Treatment programs could thus aim to target and modify interpretation biases in children with anxiety, and include parents as part of treatment.