Individuals with Down syndrome (DS) exhibit higher risk for celiac disease (CD) than general population. Although literature suggests CD could be associated with behavioural problems in both paediatric and adult age, such association has been poorly explored in children and adolescents DS. Therefore, the current study aimed to investigate differences in emotional/behavioural difficulties, adaptive skills and sleep problems between children with DS with and without CD. Data were retrospectively collected from a database including data from 381 individuals with DS (3-18years). The final sample included 65 participants, 27 with co-occurring CD and 38 age, IQ, sex and body mass index-matched controls without CD. Emotional/behavioural difficulties, adaptive skills and sleep problems were assessed through parent report questionnaires. No group differences emerged in emotional/behavioural difficulties, whereas participants in the CD group showed better adaptive skills in the practical domain than control group. Weak differences emerged in sleep problems. Youth with DS and co-occurring CD do not exhibit more emotional and behavioural problems than youth with DS without co-occurring CD but exhibit better adaptive skills in the practical domain.