Aims: To investigate parents' ability to perceive pain experienced by their offspring with Down syndrome (DS). Methods: Data were gathered by the use of the Oral Assessment in Down Syndrome Questionnaire in a cross-sectional survey design in France. A sample of parents of 204 children with DS and 161 of their siblings without DS was accrued. Results: Parental reports of difficulty discerning if their child with DS was in pain did not change with age of the child, remaining at a prevalence of 28% to 32%. Reports of difficulty discerning where that child felt pain diminished with older age from 74% to 27%. The likelihood of parents reporting difficulty discerning if and where their child with DS had pain was greater than for a sibling without DS. However, reports of pain experience for the 2 groups were the same. Moreover, different functional and dysfunctional behavioral variables were found to be predictors of these 2 pain perception variables. Conclusion: Parental perception of pain is less discriminant for children with DS than for their siblings without DS. Keywords: Down syndrome, pain perception