This study describes the characteristics of children suffering from attention deficit/hyperactivity disorder (ADHD) symptoms and evaluates the ability of primary health care to assess ADHD. A population of 494 children was referred during one year to the outpatient clinic Child and Adolescent Mental Health in Norway. Forty percent of those referred had ADHD symptoms. A clinical assessment regarding ADHD as well as general health was employed and socio-economic status was recorded. Half of the ADHD-referred children met criteria for ADHD, and among the non-ADHD children one fifth did not receive any diagnosis. Mean referral age was 10.5years; 82% were boys. The ADHD families were less educated and in more need of support from Child Welfare (CW) in the referral period (OR: 3.9; 95% CI 0.1 to 5.1). More ADHD children were not living with their families compared to the non-ADHD children. The sensitivity was 51% (96/187) regarding primary health care`s ability to recognize ADHD. Further screening programs for evaluation of ADHD are needed.