Aim: To investigate the acceptability and feasibility of adapted group therapy for anxiety in children with autism spectrum disorder in a pilot randomised controlled trial. Method: A total of 32 children aged 9-13 years were randomised to immediate or delayed therapy using the "Exploring Feelings" manual (Attwood, 2004). Child and parent groups were run in parallel, for seven weekly sessions, under the supervision of experienced psychologists. The primary blinded outcome measures addressed change in overall functioning and in severity of the primary anxiety diagnosis after 3 months. esults: Children met diagnostic criteria for 1-6 anxiety disorders (median 3). At end point, both parents and children in the immediate therapy group were more likely to report a reduction in anxiety symptoms. Fidelity of delivery of the group therapy was high, and attendance was 91%. Conclusions: This pilot trial established that children and families were willing to be recruited and randomised, the outcome measures were acceptable, the format and content of the groups were feasible within UK child and adolescent mental health services, the intervention was appreciated by families and attrition was very small.