This study examined the incidence of adverse prenatal, perinatal, and neonatal experiences amongst children with anxiety disorders, and the relationship to clinical symptomology and functional impairment in treatment-seeking children (N = 107) with a primary anxiety disorder. Anxious children had higher rates of reported maternal prescription medication use during pregnancy, maternal smoking and illness during pregnancy and neonatal complications (including neonatal intensive care and feeding issues) compared with population base rates and non-affected children. Almost one-third had early problems with sleep. Developmental problems were common with more than half having at least one area of delay. More than three quarters of anxious children had a first-degree family member with a psychiatric history. There were several associations between neonatal complications and subsequent clinical symptomology, including attention deficit hyperactivity disorder and depressive comorbidity, anxiety severity and functional impairment. Findings suggest higher rates of perinatal complications in anxious children.