The majority of studies on the effects of a diagnosis of learning disability in the family have employed traditional 'loss' and 'stress reaction' paradigms. In contrast to this approach, the current analysis employed a form of discourse analysis to explore the ways in which parents represented the 'problem' during the process of assessment of their child for an autistic spectrum disorder. The analysis suggested that parents employed three main discourses in their talk about the 'problem', which were termed the discourse of normal development, the medical discourse and the discourse of disability. The ways in which these discourses were used in constructing the 'problem', their relationship to each other and the discursive work underlying the diagnosis are discussed. Although this study focused on the specific case of autism, it is suggested that the findings could inform thinking around the complex ways in which medical diagnosis is constructed by families and extend our understanding of this important aspect of health care practice.