This study aimed to investigate the efficacy of a parent-mediated cognitive behavioural therapy (CBT) group anxiety intervention with young children with high functioning forms of autism spectrum disorder (ASD).Thirty-one children aged four to six years with ASD and anxiety were randomly assigned to treatment or waitlist control conditions. Outcomes were assessed via parent-report measures of child anxiety and emotional awareness. Parental outcomes were also investigated via self-report.At post-treatment no treatment effects were found for child or parent outcomes. However, by three-month follow-up for the completer sample, children in the treatment group demonstrated significant reductions in internalizing behaviours and there was a trend for a reduction in anxiety compared to pre-treatment. For parent outcomes, at three-month follow-up for the completer sample, no significant effects were found.Results provided preliminary evidence that children may make some gains in terms of anxiety subsequent to their parents attending a group CBT intervention for anxiety.