As part of my appointment in the department of anesthesiology at the Columbia University Medical Center, my colleagues and I have been investigating the potential role of early exposure to anesthesia in neurodevelopmental disorders. Recent animal studies have shown that commonly used anesthetic agents may have serious neurotoxic effects on the developing brain. The purpose of this study was to assess the association between surgery for hernia repair and the risk of behavioral and developmental disorders in young children. We performed a retrospective cohort analysis of children who were enrollees of the New York State Medicaid program. Our analysis involved following a birth cohort of 383 children who underwent inguinal hernia repair during the first three years of life, and a sample of 5050 children frequency-matched on age with no history of hernia-repair before age 3. After controlling for age, gender, and complicating birth-related conditions such as low birth weight, children who underwent hernia repair under three years of age were more than twice as likely as children in the comparison group to be subsequently diagnosed with a developmental or behavioral disorder (adjusted HR 2.3, 95% CI 1.3, 4.1). Our findings add to recent evidence of the potential association of surgery and its concurrent exposure to anesthetic agents with neurotoxicity and underscore the need for more rigorous clinical research on the long-term effects of surgery and anesthesia in children. More recently, we looked at the same question using a twin sibling cohort, finding attenuated but similar results.