Background: Parental beliefs about child problem behaviour have emerged as closely related to referral intentions to mental health services. Methods: This study compared beliefs of severity, impact and advice seeking for attention deficit/ hyperactivity disorder (ADHD) behaviours of parents whose preschool children present ADHD behaviours with those of parents whose children do not display such behaviours. Both parents of 295 preschoolers, aged 4-6 years, enrolled in kindergartens in Athens, filled in: (i) a questionnaire composed by a vignette describing a hypothetical 5-year-old child presenting ADHD symptoms followed by rating scales assessing dimensions of severity, impact and referral intention, and (ii) the ‘Strengths and Difficulties Questionnaire’ for screening ADHD behaviours in their own child. Results: Results showed that almost half of the parents who reported ADHD behaviours in their own child replied that they had never met a child exhibiting such behaviours. These parents also perceived such behaviours as being less severe and with less negative family impact than parents who did not report such behaviours in their own child. Conclusions: Parents whose preschool child displays ADHD behaviours tend to perceive them as normal developmental patterns and may suspend the referral of the child. Implications of these findings for early identification of ADHD are discussed.