Knowledge of the epidemiology of visual impairment in children forms one of the cornerstones of pediatric ophthalmology. In contrast to e.g. the other Nordic countries, Sweden has had no efficient and continuous registration of visually impaired children. An epidemiological study on this subject has now been done, collecting data on all children and adolescents registered at the Low Vision Clinics throughout Sweden. In this work data on 2373 visually impaired children, 0-19 years of age and living throughout Sweden are presented. Data collected in the study include sex, date of birth, county, ocular diagnosis, systemic diagnosis, classification of visual impairment, aetiology and possible additional impairments. The prevalence of visual impairment as defined by WHO was 10.9/10,000 inhabitants in the current age group. A slight male preponderance was seen compared to the total population 0-19 years. This was not reduced when only non-genetic aetiological factors were taken into consideration. A total of 45% of the children had only a moderate visual impairment (WHO category 1), whereas approximately 25% were found in WHO categories 3,4 and 5, i.e. fulfilled the requirements for blindness. Additional impairments were found in 60% of the children. Mental impairment in combination with motor impairment or mental impairment exclusively were the most common ones seen.