Introduction: The present study build on previous research that found a bidirectional relation of parenting stress and negative behavioural outcomes in children with Autism Spectrum Disorders. Aim: To investigate the mediating role of parenting self-efficacy in the relationship of parenting stress and children's behavioural and emotional problems. Materials and methods: The sample included 32 young children and their families. Sociodemographic and clinical data were collected. Hierarchical regression analysis revealed direct and indirect mediating effects. Results: Parenting self-efficacy mediated the relationship between parenting stress and children's behavioural and emotional problems in fathers only. Conclusions: We discuss potential ways targeted parenting self-efficacy intervention can support fathers. Results contribute to gain father-informed knowledge in, a research branch generally focused on mothers.