Background: Although language difficulties are one of the most distinctive characteristics of the neuropsychological profile of children with sex chromosome trisomies (SCT), the analysis of the maternal input addressed to them is a neglected topic. Aims: The present study aims to analyse the lexical, morphosyntactic, and functional features of the input addressed to children with SCT comparing them with those of the input directed to typically developing children (TD).Methods & Procedures: Participants were 38 mothers and their 8-month-old children, 19 with SCT and 19 TD children. Maternal utterances, collected during video-recorded play sessions, have been transcribed and coded. Outcomes & Results: No significant differences between groups have been found in the lexical and syntactic characteristics of maternal input. However, considering the input functional features, the proportion of directives and questions was significantly higher in the maternal input addressed to children with SCT than in the input addressed to TD children whereas the opposite pattern was found in the proportion of affect-salient speech. Conclusions & Implications: The awareness of a possible delay in their children's language development could influence the way the mothers speak to them. In particular, the functional features of maternal input could be affected. Support groups for parents of children with SCT at the preverbal stage could be useful to reassure the mothers about their role in their children's language development.