Aim of the study was to evaluate the prevalence of disturbance of activity and attention and co-morbid psychiatric disorders among the primary school children in Kaunas city. Parents and teachers of all pupils of 12 randomly selected primary schools (N=2942) were asked to fill the scales on the presence of disturbance of activity and attention symptoms in their children. Disturbance of activity and attention was diagnosed if at least 6 symptoms of hyperactivity and/or 6 symptoms of inattention were present for at least 6 months according parents reports in DuPaul-IV scale and the result of teachers CAP scale exceeded the norms for age and gender. Both scales were obtained for 2298 pupils--1096 girls and 1202 boys 6-12 years of age. Disturbance of activity and attention was diagnosed for 5.2% of primary school pupils. It was 1.9 times more frequent among boys than among girls. Prevalence of co-morbid psychiatric disorders was estimated individually interviewing suspected children and their parents using M.I.N.I. Kid questionnaire. Out of all disturbance of activity and attention diagnosed children, 52.5% were also diagnosed co-morbid psychiatric disorders, most frequently oppositional defiant disorder (31.3%) and different types of anxiety disorders (18.0%). Prevalent type of disturbance of activity and attention and co-morbid disorders was related with the age of the pupils. Symptoms of hyperactivity and co-morbid psychiatric disorders had influenced motivation of parents to seek treatment for their children. Forty percent of the parents of children, who were diagnosed disturbance of activity and attention, have applied to the mental health care professionals; most of them evaluated the help they received as partly useful (57.9%) or not useful at all (26.3%).