Objective To quantify knowledge among the general Spanish population of attention deficit hyperactivity disorder (ADHD). Material and method We developed a telephone-administered questionnaire to ask about ADHD (acronym and full name) on a spontaneous and suggested basis. Questions were asked relating to myths, symptoms, treatment, implications and healthcare professionals involved in the disease.The study sample was 770 adults (sample precision at national level 3.5) with no personal, familial or professional relationship to ADHD. Results Only 4% of the subjects spontaneously answered the question about what ADHD means, while 85.3% identified the disease after we suggested what “ADHD” meant. Only 50% admitted that the disease represents a probably genetic brain disorder. A total of 39.6% believed that there was no treatment or healthcare intervention for ADHD. The intervention most often cited as being adequate was psychological treatment (48%), followed by multimodal therapy (44%). Only 12% mentioned medication. Thus, psychological intervention was regarded as the most effective option, followed by psychoeducational measures. Most of the subjects identified the psychologist as the professional indicated to treat ADHD, followed by the pediatrician, psychiatrist and neuropediatrician. Reasonable knowledge was observed in reference to affirmations / myths in ADHD (78.3–95.3%). Conclusions There are areas for improvement among the general population regarding knowledge of ADHD, its implications and treatment.