BACKGROUND Few studies have investigated the characteristics of father language directed to typically developing children (TD), and father speech directed to children with Autism Spectrum Disorders (ASD) is largely under investigated. Considering the importance of involving fathers of children with ASD in research and clinical practice, the main purpose of this study was to investigate paternal speech directed to children with ASD compared to that of fathers of TD children. METHODS To this aim, we coded multiple functional aspects of speech during 10-min naturalistic dyadic play interactions between fathers and their preschool children with ASD (n = 20) and with TD (n = 20). RESULTS Results showed that fathers of children with ASD displayed a peculiar child-directed language that seems to reflect the effort to provide enhanced scaffolding and reduced demands while sustaining a challenging social interaction. Specifically, fathers of children with ASD used more descriptions, fewer questions in general but more questions about child internal states. Moreover, fathers adapted aspects of their information-salient speech to the severity of child impairments. CONCLUSIONS Our findings support the importance to include fathers in early developmental intervention programs for children with ASD, by underlying fathers' spontaneous adaptation to their children's needs.