Little is known about the symptoms of anxiety in very young children with autism spectrum disorders, particularly comparisons between Autistic Disorder (AD) and Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS). In the current study, toddlers (i.e., 17-37 months of age) with diagnoses of either AD (N = 159) or PDD-NOS (N = 154) were compared to atypically developing toddlers who did not meet criteria for an autism spectrum disorder (N = 200). Results indicated an overall pattern whereby toddlers with AD had more severe anxious and avoidant symptoms than either toddlers with PDD-NOS or controls. Further, toddlers with PDD-NOS were significantly more severe than controls. Additional analyses examining specific differences between the groups on anxious and avoidant items were conducted as well. Overall, toddlers with AD appear to have more severe anxiety than either those with PDD-NOS or controls, who did not differ on many items. (Contains 3 tables.)