To investigate possible correlates of generalised anxiety disorder (GAD) in young males with ASD, a test of the mediation effects of sensory features (SF) upon the association between ASD symptoms and GAD was conducted with 150 males aged 6 to 18 years. GAD data were obtained from parents of the boys and from the boys themselves; SF and ASD data were obtained from parents. Symptoms of ASD were found to influence elevated levels of parent-rated GAD indirectly through greater levels of sensory avoiding, and auditory-specific sensory behaviours correlated with parent-rated anxiety more strongly than other sensory modalities. There were no significant effects for the boys' self-rated GAD.