Introduction. Health condition is one of the basic factors determining the quality of life of children and adolescents. In early childhood, its poor condition is particularly dangerous as it can interfere with developmental processes and lead to long-term and permanent health problems. Chronic diseases are distinguished among the most common health diseases of children and adolescents. They constitute one of the most serious phenomena and problems of the modern world, resulting from the prevalence in the population, and above all from the consequences it causes in an individual and social sense. The catalog of chronic diseases includes: asthma, allergies, heart diseases, arterial hypertension, stroke, cancer, kidney diseases, multiple sclerosis, degenerative joint diseases and mental diseases. In Poland, the prevalence of chronic diseases in children aged 0-14 is found in 27%, and among adolescents aged 15-19 it is found in 23%. According to the age category of children, chronic disease was diagnosed in 23% of children aged 0-4; 30% – 5-9 years; 29% – 10-14 years. No systematic epidemiological studies are conducted in Poland on the occurrence of chronic diseases in the population of children and adolescents. Aim. The aim of the article is to present the epidemiology of selected chronic diseases among children and adolescents living in several cities of the Silesian Voivodeship. Material and methods. The research material is data from the Silesian Voivodship Office in Katowice – Department of Health. Tables were then drawn up that illustrate the epidemiology of the diseases discussed. Results. The lowest incidence rate of bronchial asthma was recorded in Sosnowiec in 2010 (18.2/10,000) and the highest in Bielsko-Biała in 2014 (91.1/10,000). In Bielsko-Biała and Katowice, the cancer incidence rate is increasing. Conclusions. The general health condition of Polish children (0-14 years) is moderately satisfactory, and children and adolescents from industrial areas, which include the Śląskie Voivodeship, are particularly exposed to more frequent incidence of respiratory diseases and various types of allergies. Currently, every fourth child has long-term health problems (26.1%), and they are more common in older children, among 10-14 year-olds (31.2%).