In the German Health Interview and Examination Survey for Children and Adolescents (KiGGS), which was conducted from 2003 to 2006, data on acute/infectious and chronic diseases were collected from a population-based sample of 17,641 subjects aged 0 to 17 years. The annual prevalence rates among acute diseases vary widely. Children and adolescents are most frequently affected by acute (infectious) respiratory conditions. 88.5 % of the surveyed children and adolescents experienced at least one episode of common cold within the last 12 months. Among the other acute respiratory infections, bronchitis and tonsillitis were the most frequently encountered conditions with 19.9 % and 18.5 %, respectively. The 12-month prevalence of otitis media and pseudocroup was 11 % and 6.6 %, respectively. 1.5 % of the children and adolescents experienced an episode of pneumonia. Apart from respiratory infections, gastrointestinal infections were very frequently stated as reasons for acute illness. Furthermore, 12.8 % of the children and adolescents experienced a herpetic infection, 7.8 % a conjunctivitis and 4.8 % a urinary tract infection. Lifetime prevalence rates of infectious diseases were as follows: pertussis 8.7 %, measles 7.4 %, mumps 4.0 %, rubella 8.5 %, varicella 70.6 %, scarlet fever 23.5 %. The various chronic somatic diseases in children and adolescents had different lifetime prevalence rates. Most frequently, children and adolescents were affected by obstructive bronchitis (13.3 %), neurodermatitis/atopic eczema (13.2 %) and hay fever (10.7 %). Scoliosis and asthma had been diagnosed by a doctor in 5.2 % and 4.7 % of subjects aged 0-17 years, respectively. The lifetime prevalence rates of the remaining diseases varied between 0.14 % for diabetes mellitus and 3.6 % for convulsions/epileptic fits. For the first time ever, these survey results provide nationwide representative information on the prevalence rates of acute/infectious and chronic diseases in children and adolescents which is based on a population-representative sample.