Anxiety disorders in children with autism spectrum disorders (ASD) are frequent, disabling and refractory to commonly known methods of treatment. Cognitive behavioral therapy (CBT) is shown to be very effective in the treatment of anxiety in normal developed children. However, children with ASD seem to respond less favourably to standard CBT anxiety programs and thus, treatment has mostly consisted of environmental therapeutic intervention and pharmacological treatment. Recent studies suggest that CBT programs specifically designed for children with ASD and anxiety are highly efficient in treating anxiety disorder and thereby reducing the co-morbid symptoms that otherwise untreated may lead to extra impairment in daily life skills. Since children with ASD often experiences difficulties in cognitive areas such as Theory of Mind, Empathy and Communication a group based manualised CBT anxiety program was adapted to suit children with ASD by modifying the approach in these areas (Cool Kids ASD). We propose to examine the effectiveness of this program using a randomized controlled trial design (RCT) analysed with the intention-to-treat approach allocating children aged 7 to 13 years to either treatment or a wait-list (WL) control condition. These groups are then followed prospectively to assess the effectiveness of the CBT program versus the WL control condition. Training anxiety reduction skills and diminishing anxiety and maybe even other co-morbid disorders in children with ASD may have great impact on the severity of the ASD, insuring better psychosocial development for the child in general and in addition, may aid in improving the quality of life for the whole family.