Relatively few measures have been examined for their psychometric properties when assessing anxiety among children with autism spectrum disorder (ASD), and the relationship between ASD and anxiety symptoms remains poorly understood. This study examined the relationship between ASD symptoms on the "Social Responsiveness Scale" ("SRS") and comorbid clinical anxiety. In a sample of 2,435 participants, parents of children with ASD and comorbid anxiety endorsed more frequent or severe ASD symptoms than parents of children without comorbid anxiety. Severity of ASD symptoms was a significant predictor of anxiety status and approached clinical significance. Implications for measurement of anxiety among children with ASD are discussed, including that areas of symptom presentation should be carefully evaluated, and that the onset or worsening of anxiety may affect ASD symptom presentation.